ABCDEFGHIJKLMNOPQRSTUVWXYZ
268 entries (amb. 23): 81 Russian, 98 Old Church Slavonic, 66 Lithuanian
-ic
Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791). Variant forms in -ick (critick, ethick) survived in English dictionaries until early 19c.
ichthyo-
word-forming element meaning "fish," from Latinized form of Greek ikhthys "a fish" (in plural, "a fish-market"), from PIE root *dhghu- "fish" (source also of Armenian jukn, Lithuanian žuvis).
ideo-
word-forming element variously used with reference to images or to ideas, from Greek idea "form; the look of a thing; a kind, sort, nature; mode, fashion," in logic, "a class, kind, sort, species" (see idea).
in- (1)
word-forming element meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant, a tendency which began in later Latin), from Latin in- "not," cognate with Greek an-, Old English un-, all from PIE root *ne- "not." In Old French and Middle English often en-, but most of these forms have not survived in Modern English, and the few that do (enemy, for instance) no longer are felt as negative. The rule of thumb in English has been to use in- with obviously Latin elements, un- with native or nativized ones.
in- (2)
element meaning "into, in, on, upon" (also im-, il-, ir- by assimilation of -n- with following consonant), from Latin in- "in," from PIE root *en "in." In Old French (and hence in Middle English) this often became en-, which in English had a strong tendency to revert to Latin in-, but not always, which accounts for pairs such as enquire/inquire. There was a native form, which in West Saxon usually appeared as on- (as in Old English onliehtan "to enlighten"), and some of those verbs survived into Middle English (such as inwrite "to inscribe"), but all now seem to be extinct. Not related to in- (1) "not," which also was a common prefix in Latin, causing confusion: to the Romans impressus could mean "pressed" or "unpressed;" inaudire meant "to hear," but inauditus meant "unheard of;" in Late Latin investigabilis could mean "that may be searched into" or "that cannot be searched into." Latin invocatus was "uncalled, uninvited," but invocare was "to call, appeal to." The trouble has continued in English; the hesitation over what is meant by inflammable being a commonly cited example. Implume (1610s) meant "to feather," but implumed (c. 1600) meant "unfeathered." Impliable can mean "capable of being implied" (1865) or "inflexible" (1734). Impartible in 17c. could mean "incapable of being divided" or "capable of being imparted." Impassionate can be "free from passion" or it can mean "strongly stirred by passion." Inanimate (adj.) is "lifeless," but Donne uses inanimate (v.) to mean "infuse with life or vigor." Irruption is "a breaking in," but irruptible is "unbreakable." In addition to improve "use to one's profit," Middle English also had a verb improve meaning "to disprove" (15c.). To inculpate is "to accuse," but inculpable means "not culpable, free from blame." Infestive has meant "troublesome, annoying" (1560s, from infest) and "not festive" (1620s). In Middle English inflexible could mean "incapable of being bent" or "capable of being swayed or moved." In 17c., informed could mean "current in information," formed, animated," or "unformed, formless" ("This was an awkward use" [OED]). Inhabited has meant "dwelt in" (1560s) and "uninhabited" (1610s); inhabitable likewise has been used on opposite senses, a confusion that goes back to Late Latin.
inter-
word-forming element used freely in English, "between, among, during," from Latin inter (prep., adv.) "among, between, betwixt, in the midst of" (also used extensively as a prefix), from PIE *enter "between, among" (source also of Sanskrit antar, Old Persian antar "among, between," Greek entera (plural) "intestines," Old Irish eter, Old Welsh ithr "among, between," Gothic undar, Old English under "under"), a comparative of root *en "in." A living prefix in English from 15c. and used with Germanic as well as Latinate words. Spelled entre- in French; most words borrowed into English in that form were re-spelled 16c. to conform with Latin except entertain, enterprise. In Latin, spelling shifted to intel- before -l-, hence intelligence, etc.
intra-
word-forming element meaning "within, inside, on the inside," from Latin preposition intra "on the inside, within, in, into;" of time, "during, in the course of," related to inter "between," from PIE *en-t(e)ro-, from root *en "in." Commonly opposed to extra-, and compare inter-. The use of intra as a prefix was rare in classical Latin.
intro-
word-forming element, from Latin intro (adv.) "in, on the inside, within, to the inside," from PIE *en-t(e)ro-, suffixed form of root *en "in."
I (pron.)
12c., a shortening of Old English ic, the first person singular nominative pronoun, from Proto-Germanic *ek (source also of Old Frisian ik, Old Norse ek, Norwegian eg, Danish jeg, Old High German ih, German ich, Gothic ik), from PIE *eg- "I," nominative form of the first person singular pronoun (source also of Sanskrit aham, Hittite uk, Latin ego (source of French Je), Greek ego, Russian ja, Lithuanian ). Reduced to i by mid-12c. in northern England, later everywhere; the form ich or ik, especially before vowels, lingered in northern England until c. 1400 and survived in southern dialects until 18c. It began to be capitalized mid-13c. to mark it as a distinct word and avoid misreading in handwritten manuscripts.
The reason for writing I is ... the orthographic habit in the middle ages of using a 'long i' (that is, j or I) whenever the letter was isolated or formed the last letter of a group; the numeral 'one' was written j or I (and three iij, etc.), just as much as the pronoun. [Otto Jespersen, "Growth and Structure of the English Language," p.233]
The dot on the "small" letter -i- began to appear in 11c. Latin manuscripts to distinguish the letter from the stroke of another letter (such as -m- or -n-). Originally a diacritic, it was reduced to a dot with the introduction of Roman type fonts. The letter -y- also was written with a top dot in Old English and early Middle English, during the centuries when -i- tended to be written with a closed loop at the top and thus was almost indistinguishable from the lower-case thorn (þ). In names of U.S. highways (by 1966) it is short for Interstate (adj.).
iceberg (n.)

1774, "glacier humped like a hill;" 1820 as "detached piece of a glacier or ice pack at sea," partial loan-translation of Dutch ijsberg, literally "ice mountain," from ijs "ice" (see ice (n.)) + berg "mountain" (from PIE root *bhergh- (2) "high," with derivatives referring to hills and hill-forts.). Similar formation in Norwegian isberg, Danish isbjerg.

Earlier English terms were sea-hill (1690s), island of ice (1610s). Phrase tip of the iceberg in a figurative sense (in allusion to most of it being unseen underwater) first recorded 1962. Iceberg lettuce attested from 1893, apparently originally a trade name.

icosahedron (n.)
"twenty-sided body," 1560s, from Latinized form of Greek eikosahedron, noun use of neuter of eikosahedros, from eikosi "twenty" + -hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit." Greek eikosi is from PIE *wikmti- "twenty," from *wi- "in half" (hence "two") + (d)kmti-, from root *dekm- "ten" (from PIE root *dekm- "ten"). Related: icosahedral.
idea (n.)
late 14c., "archetype, concept of a thing in the mind of God," from Latin idea "Platonic idea, archetype," a word in philosophy, the word (Cicero writes it in Greek) and the idea taken from Greek idea "form; the look of a thing; a kind, sort, nature; mode, fashion," in logic, "a class, kind, sort, species," from idein "to see," from PIE *wid-es-ya-, suffixed form of root *weid- "to see." In Platonic philosophy, "an archetype, or pure immaterial pattern, of which the individual objects in any one natural class are but the imperfect copies, and by participation in which they have their being" [Century Dictionary]. Meaning "mental image or picture" is from 1610s (the Greek word for it was ennoia, originally "act of thinking"), as is the sense "concept of something to be done; concept of what ought to be, differing from what is observed." Sense of "result of thinking" first recorded 1640s. Idée fixe (1836) is from French, literally "fixed idea." Through Latin the word passed into Dutch, German, Danish as idee, which also is found in English dialects. The philosophical sense has been somewhat further elaborated since 17c. by Descartes, Locke, Berkeley, Hume, Kant. Colloquial big idea (as in what's the ...) is from 1908.
idempotent (n.)
in algebra, quantity which multiplied by itself gives itself, 1870, from Latin idem "the same, identical with" (see idem) + potentem "powerful" (see potent).
ideologue (n.)
1815, in reference to the French Revolutionaries, from French ideologue, from Greek idea (see idea) + -logos (see -logy). Earlier form was ideologist (1798).
idiolect (n.)
one's personal way of using a language, 1948, from idio- "one's own, personal" + second element abstracted from dialect. Idioglottic (1888) has a sense "using words invented in one's mind" (from Greek glotta/glossa "tongue").
idiom (n.)
1580s, "form of speech peculiar to a people or place;" meaning "phrase or expression peculiar to a language" is from 1620s; from Middle French idiome (16c.) and directly from Late Latin idioma "a peculiarity in language," from Greek idioma "peculiarity, peculiar phraseology" (Fowler writes that "A manifestation of the peculiar" is "the closest possible translation of the Greek word"), from idioumai "to appropriate to oneself," from idios "personal, private," properly "particular to oneself." This is from PIE *swed-yo-, suffixed form of root *s(w)e-, pronoun of the third person and reflexive (referring back to the subject of a sentence), also used in forms denoting the speaker's social group, "(we our-)selves" (source also of Sanskrit svah, Avestan hva-, Old Persian huva "one's own," khva-data "lord," literally "created from oneself;" Greek hos "he, she, it;" Latin suescere "to accustom, get accustomed," sodalis "companion;" Old Church Slavonic svoji "his, her, its," svojaku "relative, kinsman;" Gothic swes "one's own;" Old Norse sik "oneself;" German Sein; Old Irish fein "self, himself").
[G]rammar & idiom are independent categories; being applicable to the same material, they sometimes agree & sometimes disagree about particular specimens of it; the most can be said is that what is idiomatic is far more often grammatical than ungrammatical, but that is worth saying, because grammar & idiom are sometimes treated as incompatibles .... [Fowler]
idiomatic (adj.)
1712, "peculiar to a certain language," from Latin idiomaticus, from Greek idiomatikos "peculiar, characteristic;" from idios "one's own" (see idiom) + matos "thinking, animated" (from PIE root *men- (1) "to think"). Meaning "marked by use of idioms" is from 1839.
idiopathy (n.)
"primary disease," 1690s, Modern Latin, from medical Greek idiopatheia, from idios "one's own" (see idiom) + -patheia, abstract noun formation from pathos "suffering, disease, feeling" (from PIE root *kwent(h)- "to suffer"). Related: idiopathic.
idol (n.)
mid-13c., "image of a deity as an object of (pagan) worship," from Old French idole "idol, graven image, pagan god" (11c.), from Latin idolum "image (mental or physical), form," especially "apparition, ghost," but used in Church Latin for "false god, image of a pagan deity as an object of worship." This is from Greek eidolon "mental image, apparition, phantom," also "material image, statue," in Ecclesiastical Greek," a pagan idol," from eidos "form, shape; likeness, resemblance" (see -oid). A Greek word for "image," used in Jewish and early Christian writers for "image of a false god," hence also "false god." The Germanic languages tended to form a word for it from the reverse direction, from "god" to "false god," hence "image of a false god" (compare Old English afgod, Danish afgud, Swedish avgud, Old High German abgot, compounds with af-/ab- "away, away from" (source of off) + god). The older Greek senses sometimes have been used in English. Figurative sense of "something idolized" is first recorded 1560s (in Middle English the figurative sense was "someone who is false or untrustworthy"). Meaning "a person so adored, human object of adoring devotion" is from 1590s.
idyll (n.)
also idyl, c. 1600, "short, picturesque pastoral poem," from French idylle (16c.) or directly Latin idyllium, from Greek eidyllion "short, descriptive poem, usually of rustic or pastoral type," literally "a little picture," diminutive of eidos "form" (see -oid).
igneous (adj.)
1660s, "pertaining to or resembling fire," from Latin igneus "of fire, fiery; on fire; burning hot," figuratively "ardent, vehement," from ignis "fire, a fire," extended to "brightness, splendor, glow;" figuratively "rage, fury, passion," from PIE root *egni- "fire" (source also of Sanskrit agnih "fire, sacrificial fire," Old Church Slavonic ogni, Lithuanian ugnis "fire"). Geological meaning "produced by volcanic forces" is from 1791, originally in distinction from aqueous. Earlier in the sense "fiery" were ignean (1630s), ignic (1610s).
ignoble (adj.)
mid-15c., "of low birth;" 1590s as "not honorable, of low character;" from Middle French ignoble (14c.), from Latin ignobilis "unknown, undistinguished, obscure; of base birth, not noble," from assimilated form of in- "not, opposite of" (see in- (1)) + gnobilis "well-known, famous, renowned, of superior birth," from PIE root *gno- "to know." Related: Ignobly; ignobility.
ignorant (adj.)
late 14c., "lacking wisdom or knowledge; unaware," from Old French ignorant (14c.), from Latin ignorantem (nominative ignorans) "not knowing, ignorant," present participle of ignorare "not to know, to be unacquainted; mistake, misunderstand; take no notice of, pay no attention to," from assimilated form of in- "not, opposite of" (see in- (1)) + Old Latin gnarus "aware, acquainted with" (source also of Classical Latin noscere "to know," notus "known"), from Proto-Latin suffixed form *gno-ro-, suffixed form of PIE root *gno- "to know." Also see uncouth. Form influenced by related Latin ignotus "unknown, strange, unrecognized, unfamiliar." Colloquial sense of "ill-mannered, uncouth, knowing nothing of good manners" attested by 1886. As a noun, "ignorant person," from mid-15c. Related: Ignorantly.
ignore (v.)
1610s, "not to know, to be ignorant of," from French ignorer "be unaware of" (14c.), or directly from Latin ignorare "not to know, be unacquainted; take no notice of, disregard" (see ignorant). The original sense in English is obsolete. Sense of "pass over without notice, pay no attention to" in English first recorded 1801 (Barnhart says "probably a dictionary word"), and OED indicates it was uncommon before c. 1850. Related: Ignored; ignoring.
ileus (n.)
painful intestinal condition, 1706, from Latin ileus "severe colic," from Greek eileos "colic," from eilein "to turn, squeeze," from PIE root *wel- (3) "to turn, revolve."
illumination (n.)
late 14c., "spiritual enlightenment," from Late Latin illuminationem (nominative illuminatio), noun of action from past participle stem of Latin illuminare "to throw into light, make bright, light up;" figuratively, in rhetoric, "to set off, illustrate," from assimilated form of in- "in, into" (from PIE root *en "in") + lumen (genitive luminis) "light," from suffixed form of PIE root *leuk- "light, brightness." Meaning "action of lighting" in English is from 1560s; sense of "intellectual enlightenment" is from 1630s.
illustration (n.)
c. 1400, "a shining;" early 15c., "a manifestation;" mid-15c., "a spiritual illumination," from Old French illustration "apparition, appearance" (13c.) and directly from Latin illustrationem (nominative illustratio) "vivid representation" (in writing), literally "an enlightening," from past participle stem of illustrare "light up, make light, illuminate;" figuratively "make clear, disclose, explain; adorn, render distinguished," from assimilated form of in- "in" (from PIE root *en "in") + lustrare "make bright, illuminate," from suffixed form of PIE root *leuk- "light, brightness." Mental sense of "act of making clear in the mind" is from 1580s. Meaning "an illustrative picture" is from 1816.
imbibe (v.)
late 14c., from Old French imbiber, embiber "to soak into," and directly from Latin imbibere "absorb, drink in, inhale," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + bibere "to drink," related to potare "to drink," from PIE root *po(i)- "to drink." Figurative sense of "mentally drink in" (knowledge, ideas, etc.) was the main one in classical Latin, first attested in English 1550s. Related: Imbibed; imbibing.
imbroglio (n.)
1750, "a jumble;" 1818 as "complicated misunderstanding, intricate entanglement" (of persons, nations, etc.), from Italian imbroglio, from imbrogliare "confuse, tangle," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + brogliare "embroil," probably from Middle French brouiller "confuse" (see broil (v.2); also compare embroil).
imbrue (v.)
early 15c., "to soak, steep;" mid-15c., "to stain, soil," from Old French embruer "to moisten," which probably is a metathesis of embevrer "give to drink, make drunk," from em- (see em-) + -bevrer, ultimately from Latin bibere "to drink" (from PIE root *po(i)- "to drink"). Or perhaps from Old French embroue "soiled," ultimately from boue "mud, dirt."
immanent (adj.)

"indwelling, remaining within, inherent," 1530s, via French immanent (14c.) or directly from Late Latin immanens, present participle of immanere "to dwell in, remain in," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + Latin manere "to dwell" (from PIE root *men- (3) "to remain"). In medieval philosophy contrasted with transitive; later with transcendent. Related: Immanently.

imminence (n.)

c. 1600, from Late Latin imminentia, from Latin imminentem (nominative imminens) "overhanging; impending," present participle of imminere "to overhang, lean towards," hence "be near to," also "threaten, menace, impend, be at hand, be about to happen," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + -minere "jut out," which is related to mons "hill" (from PIE root *men- (2) "to project"). 

imminent (adj.)

1520s, from Middle French imminent (14c.) and directly from Latin imminentem (nominative imminens) "overhanging; impending," present participle of imminere "to overhang, lean towards," hence "be near to," also "threaten, menace, impend, be at hand, be about to happen," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + -minere "jut out," which is related to mons "hill" (from PIE root *men- (2) "to project"). Related: Imminently.

immiscible (adj.)

"incapable of being mixed" (as oil and water are), 1670s, from assimilated form of in- "not, opposite of" (see in- (1)) + miscible, from Latin miscere "to mix" (from PIE root *meik- "to mix").

immolate (v.)
1540s, "to sacrifice, kill as a victim," from Latin immolatus, past participle of immolare "to sacrifice," originally "to sprinkle with sacrificial meal," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + mola (salsa) "(sacrificial) meal," related to molere "to grind" (from PIE root *mele- "to crush, grind"). Related: Immolated; immolating.
immortal (adj.)
late 14c., "deathless," from Latin immortalis "deathless, undying" (of gods), "imperishable, endless" (of fame, love, work, etc.), from assimilated form of in- "not, opposite of" (see in- (1)) + mortalis "mortal" (from PIE root *mer- "to rub away, harm," also "to die" and forming words referring to death and to beings subject to death). In reference to fame, literature, etc., "unceasing, destined to endure forever, never to be forgotten, lasting a long time," attested from early 15c. (also in classical Latin). As a noun, "an immortal being," from 1680s.
immune (adj.)
mid-15c., "free, exempt" (from taxes, tithes, sin, etc.), from Latin immunis "exempt from public service, untaxed; unburdened, not tributary," literally ""not paying a share," from assimilated form of in- "not, opposite of" (see in- (1)) + munis "performing services" (compare municipal), from PIE *moi-n-es-, suffixed form of root *mei- (1) "to change, go, move." Specific modern medical sense of "exempt (from a disease)," typically because of inoculation, is from 1881, a back-formation from immunity. Immune system attested by 1917.
immutable (adj.)
early 15c., "unchanging, unalterable," from Old French immutable (Modern French immuable), and directly from Latin immutabilis "unchangeable, unalterable," from assimilated form of in- "not, opposite of" (see in- (1)) + mutabilis "changeable," from mutare "to change" (from PIE root *mei- (1) "to change, go, move"). Related: Immutably.
imp (n.)
Old English impe, impa "young shoot, graft," from impian "to graft," probably an early Germanic borrowing from Vulgar Latin *imptus, from Late Latin impotus "implanted," from Greek emphytos, verbal adjective formed from emphyein "implant," from em- "in" + phyein "to bring forth, make grow," from PIE root *bheue- "to be, exist, grow." Compare Swedish ymp, Danish ympe "graft." The sense of the word has shifted from plants to people, via the meaning "child, offspring" (late 14c., now obsolete), from the notion of "newness." The current meaning "little devil" is attested from 1580s, from common pejorative phrases such as imp of Satan. The extension from this to "mischievous or pert child" (1640s) unconsciously turns the word back toward its Middle English sense.
Suche appereth as aungelles, but in very dede they be ymps of serpentes. [Wynkyn de Worde, "The Pilgrimage of Perfection," 1526]
impact (v.)
c. 1600, "press closely into something," from Latin impactus, past participle of impingere "to push into, drive into, strike against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pangere "to fix, fasten" (from PIE root *pag- "to fasten"). Original sense is preserved in impacted teeth. Sense of "strike forcefully against something" first recorded 1916. Figurative sense of "have a forceful effect on" is from 1935. Related: Impacting.
impact (n.)
1738, "collision, act of striking against, striking of one thing against another," from impact (v.). Figurative sense of "forceful impression" is from 1817 (Coleridge).
impair (v.)
late 14c., a re-Latinizing of earlier ampayre, apeyre "make worse, cause to deteriorate" (c. 1300), from Old French empeirier "make worse" (Modern French empirer), from Vulgar Latin *impeiorare "make worse," from assimilated form of in- "into, in" (from PIE root *en "in") + Late Latin peiorare "make worse," from peior "worse," perhaps originally "stumbling," from PIE *ped-yos-, suffixed (comparative) of *ped- "to walk, stumble, impair," from root *ped- "foot. In reference to driving under the influence of alcohol, first recorded 1951 in Canadian English. Related: Impaired; impairing.
impale (v.)
1520s, "to enclose with stakes, fence in" (a sense continued in specialized uses into 19c.), from Middle French empaler or directly from Medieval Latin impalare "to push onto a stake," from assimilated form of in- "into, in" (from PIE root *en "in") + Latin palus "a stake, prop, stay; wooden post, pole," from PIE *pak-slo-, from root *pag- "to fasten." Sense of "pierce with a pointed stake" (as torture or capital punishment) first recorded 1610s. Related: Impaled; impaling.
impanate (adj.)
"present in the (consecrated) bread," 1540s, from Church Latin impanatus, past participle of impanare "to embody in bread," from assmiliated form of in- "in, into" (from PIE root *en "in") + panis "bread," from PIE root *pa- "to feed." Related: Impanation (1540s), from Medieval Latin impanationem. The Adessenarians (1751, from Latin adesse "be present," from ad- "to" + esse "be") believed in the real presence of Christ's body in the eucharist, not by transubstantiation but by impanation.
impart (v.)

early 15c., "to give a part of (one's possessions);" late 15c., "to share, take part in," from Old French empartir, impartir "assign, allot, allocate, share out" (14c.), from Late Latin impartire (also impertire) "to share in, divide with another; communicate," from assimilated form of in- "into, in" (from PIE root *en "in") + partire "to divide, part" (from pars "a part, piece, a share," from PIE root *pere- (2) "to grant, allot").

Meaning "communicate as knowledge or information" is from 1540s; the word was not originally restricted to immaterial things but now usually is only in reference to qualities. Related: Imparted; imparting; impartment.

impeach (v.)
formerly also empeach, late 14c., "to impede, hinder, prevent," from Anglo-French empecher, Old French empeechier "to hinder, stop, impede; capture, trap, ensnare" (12c., Modern French empêcher), from Late Latin impedicare "to fetter, catch, entangle," from assimilated form of in- "into, in" (from PIE root *en "in") + Latin pedica "a shackle, fetter," from pes (genitive pedis) "foot" (from PIE root *ped- "foot"). Sense of "accuse a public officer of misconduct" first recorded 1560s, perhaps via Medieval Latin confusion of the word with Latin impetere "attack, accuse" (see impetus). Related: Impeached; impeaching.
impeccable (adj.)
1530s, "not capable of sin," from Middle French impeccable (15c.) or directly from Late Latin impeccabilis "not liable to sin," from assimilated form of in- "not, opposite of" (see in- (1)) + peccare "to sin" (see peccadillo). Meaning "faultless" is from 1610s. Related: Impeccably; impeccant; impeccancy.
impede (v.)
c. 1600, back-formation from impediment, or else from Latin impedire "impede, be in the way, hinder, detain," literally "to shackle the feet," from assimilated form of in- "into, in" (from PIE root *en "in") + pes (genitive pedis) "foot," from PIE root *ped- "foot." Related: Impeded; impedes; impeding; impedient.
impediment (n.)
c. 1400, from Old French empedement or directly from Latin impedimentum "hindrance," from impedire "impede," literally "to shackle the feet," from assimilated form of in- "into, in" (from PIE root *en "in") + pes (genitive pedis) "foot," from PIE root *ped- "foot." Related: Impedimental.
impel (v.)
early 15c., from Latin impellere "to push, strike against; set in motion, drive forward, urge on," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pellere "to push, drive" (from PIE root *pel- (5) "to thrust, strike, drive"). Related: Impelled; impelling.
impend (v.)
"be about to happen" (usually of something unwanted), 1590s, from Latin impendere "to hang over;" figuratively "to be imminent, be near," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pendere "to hang" (from PIE root *(s)pen- "to draw, stretch, spin"). Literal sense in English is by 1780. Related: Impended; impending.
imperative (adj.)

1520s, in grammar, from Late Latin imperativus "pertaining to a command," from imperat-, past participle stem of imperare "to command, requisition," from assimilated form of in- "into, in" (from PIE root *en "in") + parare "to arrange, prepare, adorn" (from PIE root *pere- (1) "to produce, procure").

imperative (n.)
mid-15c., in grammar; later "something imperative" (c. 1600), from Old French imperatif in the grammatical sense (13c.) and directly from Late Latin imperativus (see imperative (adj.)). In philosophy from 1796.
imperator (n.)
"absolute ruler," 1580s, from Latin imperator "commander-in-chief, leader, master," agent noun from stem of imperare "to command" (see imperative (adj.)). In the Roman republic, a holder of military command during active service, also a title bestowed on victorious generals; in the Roman Empire, the emperor as commander-in-chief of the armies. Related: Imperatorial.
imperial (adj.)

late 14c., "having a commanding quality," from Old French imperial, emperial "imperial; princely, splendid; strong, powerful" (12c.), from Latin imperialis "of the empire or emperor," from imperium "empire" (see empire).


Meaning "pertaining to an empire" (especially Rome's) is from late 14c.; by 1774 of Britain's. Meaning "of imposing size or excellence" is from 1731. Imperial presidency in a U.S. context traces to Arthur Schlesinger Jr.'s book on the Nixon administration (1974). Related: Imperially. The noun is from 1520s as "member of the emperor's party;" 1670s as the name of gold coins issued by various imperial authorities.

impervious (adj.)
1640s, from Latin impervius "not to be traverse, that cannot be passed through, impassible," from assimilated form of in- "not, opposite of" (see in- (1)) + pervius "letting things through, that can be passed through," from per "through" (from PIE root *per- (1) "forward," hence "through") + via "road" (see via (adv.)). Related: Imperviously; imperviousness.
impetigo (n.)
pustular disease of the skin, late 14c., from Latin impetigo "skin eruption," from impetere "to attack" (see impetus). Originally used generally; the sense narrowed in modern times to specific diseases. Related: Impetiginous.
impetuous (adj.)
late 14c., "hot-tempered, fierce;" late 15c., "done or given with a rush of force," from Old French impetuos (13c., Modern French impétueux) and directly from Late Latin impetuosus "impetuous, violent" (source also of Spanish and Italian impetuoso), from Latin impetus "attack" (see impetus). Related: Impetuously; impetuousness.
impetus (n.)

early 15c., impetous "rapid movement, rush;" 1640s, with modern spelling, "force with which a body moves, driving force," from Latin impetus "an attack, assault; rapid motion; an impulse; violence, vigor, force;" figuratively "ardor, passion," from impetere "to attack," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + petere "aim for, rush at" (from PIE root *pet- "to rush, to fly").

impinge (v.)
1530s, "fasten or fix forcibly," from Latin impingere "drive into, strike against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pangere "to fix, fasten" (from PIE root *pag- "to fasten"). Sense of "encroach, infringe" first recorded 1738. Related: Impinged; impinging; impingent.
implant (v.)
1540s, "to plant in" (abstractly, of ideas, emotions, etc.), from Middle French implanter "to insert, engraft" (alongside Old French emplanter "to plant"), literally "plant in," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + planter "to plant" (see plant (n.)). Meaning "surgically implant (something) in the body" is from 1886, originally of teeth. Implanted is attested from early 15c., probably based on Medieval Latin implantus. Related: Implanting.
implant (n.)
1890, "thing implanted;" 1941 as "action of implanting," from implant (v.). Related: Implants, which is attested by 1981 as short for breast implants (1976).
implement (v.)
"to complete, perform, carry into effect," 1707, originally chiefly in Scottish English, where the noun was a legal term meaning "fulfillment," from implement (n.). It spawned implementation, which is first recorded 1913. Related: Implemented; implementing.
implement (n.)
mid-15c., "supplementary payment, amount needed to complete repayment," from Late Latin implementem "a filling up" (as with provisions), from Latin implere "to fill, fill up, make full; fatten; fulfill, satisfy," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plere "to fill" (from PIE root *pele- (1) "to fill"). Sense of "workman's tool, utensil of a trade, things necessary to do work" is 1530s. The underlying connection of the senses is "whatever may supply a want, that which fills up a need." Related: Implemental; implements.
implex (adj.)
"intricate, complicated," 1710, from Latin implexus "interwoven, entwined," past participle of implectere, from assimilated form of in- "in" (from PIE root *en "in") + plectere "to plait, twine, braid" (from suffixed form of PIE root *plek- "to plait"). Used by 18c. critics in reference to plots.
implicate (v.)
early 15c., "to convey (truth) in a fable," from Latin implicatus, past participle of implicare "to involve, entwine, entangle, embrace," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). From c. 1600 as "intertwine, wreathe." Meaning "involve (someone) in a crime, charge, etc.; show (someone) to be involved" is from 1797. Related: Implicated; implicating.
implication (n.)
early 15c., "action of entangling," from Latin implicationem (nominative implicatio) "an interweaving, an entanglement," noun of state from past participle stem of implicare "involve, entangle; embrace; connect closely, associate," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). Meaning "that which is implied (but not expressed), inference drawn from what is observed" is from 1550s.
implicit (adj.)
1590s, "implied, resting on inference," from Middle French implicite and directly from Latin implicitus, later variant of implicatus "entangled, confused, involved," past participle of implicare "entangle, involve," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). From c. 1600 as "resulting from perfect confidence (in authority), unquestioning" (especially of faith).
imply (v.)
late 14c., implien, emplien "to enfold, enwrap, entangle" (the classical Latin sense), from Old French emplier, from Latin implicare "involve, enfold, entangle," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). Meaning "to involve something unstated as a logical consequence" first recorded c. 1400; that of "to hint at" is from 1580s. Related: Implied; implying. The distinction between imply and infer is in "What do you imply by that remark?" but, "What am I to infer from that remark?" Or, as Century Dictionary puts it, "An action implies ability or preparation, but involves consequences."
import (n.)
1580s, "consequence, importance;" 1680s, "that which is imported;" both from import (v.).
import (v.)

early 15c., "signify, show, bear or convey in meaning," from Latin importare "bring in, convey, bring in from abroad," from assimilated form of in- "into, in" (from PIE root *en "in") + portare "to carry," from PIE root *per- (2) "to lead, pass over." In English, the sense of "bring from another state or land," especially "bring in goods from abroad" first recorded 1540s. As "be important" from 1580s. Related: Imported; importing.

important (adj.)

mid-15c., from Middle French important and directly from Medieval Latin importantem (nominative importans) "important, momentous," present-participle adjective from importare "be significant in," from Latin importare "bring in, convey, bring in from abroad," from assimilated form of in- "into, in" (from PIE root *en "in") + portare "to carry," from PIE root *per- (2) "to lead, pass over." Meaning "pretentious, pompous" is from 1713. Related: Importantly.

importune (v.)
"harass with solicitation, demand persistently," 1520s, back-formation from importunity, or else from Middle French importuner, from Medieval Latin importunari "to make oneself troublesome," from Latin importunus "unfit, unfavorable, troublesome," literally "having no harbor" (thus "difficult to access"), from assimilated form of in- "not, opposite of" (see in- (1)) + portus "harbor" (see port (n.1)). Related: Importuned; importuning. As an adjective from early 15c. Portunus was the Roman deity of harbours; hence Portunium "temple of Portunus."
impotent (adj.)
late 14c., "physically weak, enfeebled, crippled," from Old French impotent "powerless, weak, incapable of doing," from Latin imponentem (nominative impotens) "lacking control, powerless, feeble; lacking self-control," from assimilated form of in- "not, opposite of" (see in- (1)) + ponentem (nominative potens) "potent" (see potent). Meaning "having no power to accomplish anything" is from mid-15c.; that of "completely lacking in sexual power" (of males) is from mid-15c. Middle English also had a native term for this: Cunt-beaten (mid-15c.). The figurative sense in Latin was "without self-control, headstrong, violent, ungovernable, lacking self-restraint," which sometimes is found in English (OED cites examples from Spenser, Massinger, Dryden, and Pope). Related: Impotently.
impoverish (v.)
early 15c., empoverischen, from Old French empoveriss-, stem of empoverir, from em- + povre "poor" (see poor (adj.)). In the same sense Middle English also had empover (early 15c., from Old French enpoverir). Related: Impoverished; impoverishing.
imprecation (n.)

mid-15c., "a curse, cursing," from Latin imprecationem (nominative imprecatio) "an invoking of evil," noun of action from past participle stem of imprecari "invoke, pray, call down upon," from assimilated form of in- "into, in, within" (from PIE root *en "in") + precari "to pray, ask, beg, request" (from PIE root *prek- "to ask, entreat"). "Current limited sense is characteristic of human nature" [Weekley].

impregnate (v.)
c. 1600, "to fill with an ingredient, spirit, etc.;" 1640s as "make (a female) pregnant), from Late Latin impraegnatus "pregnant," past participle of impraegnare "to render pregnant," from assimilated form of in- "into, in" (from PIE root *en "in") + praegnare "make pregnant" (see pregnant). Earlier in same sense was impregn (1530s), which OED marks as "now only in poetic use."
impresario (n.)

"one who organizes public entertainments," 1746, from Italian impresario "operatic manager," literally "undertaker (of a business)," from impresa "undertaking, enterprise, attempt," fem. of impreso, past participle of imprendere "undertake," from Vulgar Latin imprendere, from assimilated form of in- "into, in, on, onto" (from PIE root *en "in") + prehendere "to grasp" (from prae- "before;" see pre-, + -hendere, from PIE root *ghend- "to seize, take").

impress (v.1)

late 14c., "have a strong effect on the mind or heart, to stamp deeply in the mind," from Latin impressus, past participle of imprimere "press into or upon, stamp," also figurative, from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike"). Literal sense of "to apply with pressure, make a permanent image in, indent, imprint" is from early 15c. in English. Related: Impressed; impressing.

impress (v.2)
"levy for military service," 1590s, from assimilated form of in- (2) "into, in" + press (v.2). Related: Impressed; impressing.
impress (n.)
"act of impressing" (1590s), also "characteristic mark" (1580s), from impress (v.1). From 1620s as "badge worn by nobility or their retainers," from Italian impresa; earlier in English in this sense as impreso, imprese (1580s).
imprimatur (n.)

"licence to print, granted by a licenser of the press," 1640, Modern Latin, literally "let it be printed," the formula of a book licenser, third person singular present subjunctive passive of Latin imprimere "to print, engrave, stamp; press upon, press against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike"). Originally of state licence to print books, later only of Roman Catholic Church.

imprint (n.)
mid-15c., emprente "an imprint or mark, impression made by printing or stamping," from Old French empreinte "mark, impression, imprint" (see imprint (v.)). Meaning "publication information of a book" (1790) is directly from the verb.
imprint (v.)

formerly also emprint, late 14c., imprenten, emprenten, "to mark by pressure, stamp; to impress on the mind or memory," from Old French empreinter "to stamp, engrave, imprint," from empreinte "mark, impression, imprint" (13c.), noun use of fem. past participle of eimpreindre "to impress, imprint," from Vulgar Latin *impremere, from Latin imprimere "to impress, imprint," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").

improbity (n.)
"want of integrity," 1590s, from Latin improbitas "badness, dishonesty," from assimilated form of in- "not" (see in- (1)) + probitas "uprightness, honesty," from probus "worthy, good" (see prove).
impromptu (adv.)

1660s, from French impromptu (1650s), from Latin in promptu "in readiness," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + promptu, ablative of promptus "ready, prepared; set forth, brought forward," from past participle of promere "to bring out," from pro "before, forward, for" (see pro-) + emere "obtain" (from PIE root *em- "to take, distribute"). From 1764 as an adjective; as a noun from 1680s.

improve (v.)

late 15c., "to use to one's profit, to increase (income)," from Anglo-French emprouwer "to turn to profit" (late 13c.), from Old French en-, a causative prefix or from em-, + prou "profit," from Latin prode "advantageous" (see proud (adj.)).

Spelling with -v- was rare before 17c.; it apparently arose from confusion of -v- and -u-. Spelling otherwise deformed by influence of words in -prove. Meaning "make better, raise to a better quality or condition" first recorded 1610s. Intransitive sense "get better" is from 1727. Phrase improve the occasion retains the etymological sense. Meaning "to turn land to profit" (by clearing it, erecting buildings, etc.) was in Anglo-French (13c.) and survived or was revived in the American colonies and Australia. Hence, "make good use of, occupy (a place) and convert to some purpose."

improvisation (n.)
"act of improvising musically," 1786, from French improvisation, from improviser "compose or say extemporaneously" (17c.), from Italian improvisare "to sing or speak extempore," from Latin improviso "unforeseen; not studied or prepared beforehand," ablative of improvisus "not foreseen, unexpected," from assimilated form of in- "not, opposite of" (see in- (1)) + provisus "foreseen," also "provided," past participle of providere "foresee, provide" (see provide). From music the sense expanded to a general meaning "do or perform on the spur of the moment."
improvise (v.)

1808, from Italian improvisare "to sing or speak extempore," from Latin improviso "unforeseen; not studied or prepared beforehand," ablative of improvisus "not foreseen, unexpected," from assimilated form of in- "not, opposite of" (see in- (1)) + provisus "foreseen," also "provided," past participle of providere "foresee, provide" (see provide). Also partly from French improviser.

Regarded as a foreign word and generally printed in italics in English in early 19c. Other verbs were improvisate (1825), improvisatorize (1828), the latter from improvisator "one of a class of noted extemporaneous poets of Italy" (1765), the earliest word of the group to appear in English. Related: Improvised; improvising.

The metre generally adopted for these compositions was the ottava rima, although Doni affirms that the Florentines used to improvise* in all kinds of measure.
* This new-coined verb is introduced to avoid circumlocution, for this time only: therefore I hope your readers will excuse it. I conjugate it after the regular verb to revise -- improvise -- improvising -- improvised. ["On the Improvvisatori of Italy," in "The Athenaeum," August 1808]
Our travellers have introduced among us the substantive improvisatore unaltered from the Italian; but as the verb improvisare could not be received without alteration, we lack it altogether, though the usage of the noun requires that of the verb: I here endeavor to supply the deficience by the word improvisate. [Samuel Oliver Jr., "A General, Critical Grammar of the Inglish Language," London, 1825]
impulse (n.)
early 15c., "an act of impelling, a thrust, push," from Latin impulsus "a push against, pressure, shock," figuratively "incitement, instigation," past participle of impellere "to strike against, push against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pellere "to push, drive" (from PIE root *pel- (5) "to thrust, strike, drive"). Meaning "a stimulus in the mind to action, arising from some state or feeling" is first recorded 1640s. As an adjective, in reference to purchases made on impulse, 1955 (in impulse buyer).
impute (v.)

early 15c., from Old French imputer, emputer (14c.) and directly from Latin imputare "to reckon, make account of, charge, ascribe," from assimilated form of in- "in, into" (from PIE root *en "in") + putare "to trim, prune; reckon, clear up, settle (an account)," from PIE *puto- "cut, struck," suffixed form of root *pau- (2) "to cut, strike, stamp." Related: Imputed; imputing.

in fieri
legal Latin, "in the process of being done," from fieri "to come into being, become," used as passive of facere "to make, do" (from PIE root *dhe- "to set, put").
incarnadine
1590s (adj.) "flesh-colored, carnation-colored, pale red, pink," from French incarnadin (16c.), from dialectal Italian incarnadino "flesh-color," from Late Latin incarnatio (see incarnation). The adjective now is archaic or obsolete. The word survives as a verb taken from the adjective, which properly would mean "to make flesh-colored," but means "make red" instead, the sense and the existence of the verb being entirely traceable to Lady Macbeth ("Macbeth" II ii.) in 1605. Its direct root might be the noun incarnadine "blood-red; flesh-color," though this is not attested until 1620s.
incarnate (adj.)
late 14c., "embodied in flesh, in human or bodily form" (of souls, spirits, etc.), from Late Latin incarnatus "made flesh," a frequent word among early Christian writers, past-participle adjective from Latin incarnare "to make flesh" (see incarnation). Of qualities or abstractions, 1530s.
incarnate (v.)
"clothe or embody in flesh," 1530s, a back-formation from incarnation, or else from Late Latin incarnatus "made flesh," past participle of incarnare "to make flesh; be made flesh." Meaning "make or form flesh" (as in healing a wound) is from 1670s. Related: Incarnated; incarnating.
incarnation (n.)
c. 1300, "embodiment of God in the person of Christ," from Old French incarnacion "the Incarnation" (12c.), from Late Latin incarnationem (nominative incarnatio), "act of being made flesh" (used by Church writers especially in reference to God in Christ; source also of Spanish encarnacion, Italian incarnazione), noun of action from past participle stem of Late Latin incarnari "be made flesh," from in- "in" (from PIE root *en "in") + caro (genitive carnis) "flesh" (originally "a piece of flesh," from PIE root *sker- (1) "to cut"). Glossed in Old English as inflæscnes, inlichomung. As "person or thing that is the embodiment" (of some quality, deity, etc.) from 1742.
incessant (adj.)
mid-15c., from Old French *incessant or directly from Late Latin incessantem (nominative incessans) "unceasing," from Latin in- "not" (see in- (1)) + cessans, present participle of cessare "to cease, go slow, give over, leave off, be idle," frequentative of cedere (past participle cessus) "go away, withdraw, yield" (from PIE root *ked- "to go, yield"). Related: Incessantly (early 15c.).
inch (n.1)
"linear measure, one-twelfth of a foot," late Old English ynce, Middle English unche (current spelling c. 1300), from Latin uncia "a twelfth part," from unus "one" (from PIE root *oi-no- "one, unique"). An early Anglo-Saxon borrowing from Latin; not found in other Germanic languages. Transferred and figurative sense of "a very small amount, small quantity" is attested from mid-14c. As the unit of measure of rainfall from 1845. Sometimes misdivided in Middle English as a neynche. Every inch "in every respect" is from early 15c. For phrase give him an inch ... see ell.
incline (v.)
in early use also encline, c. 1300, "to bend or bow toward," from Old French encliner "to lean, bend, bow down," from Latin inclinare "to cause to lean; bend, incline, turn, divert," from in- "into, in, on, upon" (from PIE root *en "in") + clinare "to bend," from PIE *klein-, suffixed form of root *klei- "to lean." Metaphoric sense of "have a mental disposition toward" is early 15c. in English (but existed in classical Latin). Related: Inclined; inclining.
incline (n.)
c. 1600, "mental tendency," from incline (v.). The literal meaning "slant, slope" is attested from 1846 in railroading.
include (v.)
early 15c., "to shut (someone or something) in materially, enclose, imprison, confine," also "to have (something) as a constituent part," from Latin includere "to shut in, enclose, imprison, insert," from in- "in" (from PIE root *en "in") + claudere "to shut" (see close (v.)). The alleged Sam Goldwyn-ism "Include me out" is attested from 1937. Related: Included; including.
incognito (adj./adv.)
1640s as both adjective ("disguised under an assumed name and character") and adverb ("unknown, with concealed identity"), from Italian incognito "unknown," especially in connection with traveling, from Latin incognitus "unknown, not investigated," from in- "not, opposite of, without" (see in- (1)) + cognitus, past participle of cognoscere "to get to know" (see cognizance). Also as a noun, "an unknown man" (1630s). Feminine form incognita was maintained through 19c. by those scrupulous about Latin. Incog was a common 18c. colloquial abbreviation.
incommunicado (adj./adv.)
1844, American English, from Spanish incomunicado, past participle of incomunicar "deprive of communication," from in- "not" (see in- (1)) + comunicar "communicate," from Latin communicare "to share, impart," literally "to make common," related to communis "common, public, general" (see common (adj.)).
incondite (adj.)
1630s, "ill-made," earlier "crude, upolished" (1530s), from Latin inconditus "disordered, uncouth," from in- "not, opposite of" (see in- (1)) + conditus, past participle of condere "put together," from assimilated form of com- "together" (see com-) + -dere "put," from PIE root *dhe- "to put, place." Applied from 1845 to natural utterances ("oh!") from Latin (vox) incondita.
incorrigible (adj.)
mid-14c., "incurable (of diseases, venom, etc.); extravagant (of expense); implacable (of hearts)," from Old French incorrigible "perfect, beyond rebuke or discipline" (14c.) or directly from Latin incorrigibilis "not to be corrected," from in- "not, opposite of" (see in- (1)) + corrigibilis, from corrigere "to correct," from com-, intensive prefix (see com-), + regere "to lead straight, rule" (from PIE root *reg- "move in a straight line," with derivatives meaning "to direct in a straight line," thus "to lead, rule"). From mid-15c. as "incapable of improvement" (of persons). Related: Incorrigibly. As a noun, from 1746.
increase (v.)
mid-14c., encresen, "become greater in size or number" (intransitive); late 14c., "cause to grow, enlarge" (transitive), from Anglo-French encress-, Old French encreiss-, present participle stem of encreistre, from Latin increscere "to increase, to grow upon, grow over, swell, grow into," from in- "in" (from PIE root *en "in") + crescere "to grow" (from PIE root *ker- (2) "to grow"). Modern English restored the Latin spelling 16c. Related: Increased; increasing.
increase (n.)
late 14c., "action of increasing; results of an increasing," from increase (v.) or from verbs formed from the noun in Old French or Anglo-French. The stress shifted from 18c. to distinguish it from the verb.
incroyable (n.)
1796, from French incroyable, literally "incredible" (15c.), from in- "not, opposite of, without" (see in- (1)) + croire "to believe," from Latin credere "to believe" (see credo). A name for the French fop or dandy of the period of the Directory (1795-99). Said to be so called from their extravagant dress, and also, according to OED, from a favorite expression among them ("C'est vraiment incroyable").
incunabula (n.)

1824, a Latin word meaning "swaddling clothes," also, figuratively, "childhood, beginnings, birthplace, place where a thing had its earliest development, the beginning of anything;" especially "early printed book using movable-type technology," From Gutenberg's beginning c. 1439 to the close of the year 1500. Latin incunabula "a cradle; a birthplace," figuratively "rudiments or beginnings," is from in "in" (from PIE root *en "in") + cunabula, diminutive of cunae "cradle," from PIE *koi-na-, suffixed form of root *kei- (1) "to lie," also forming words for "bed, couch."

Interest in collecting them began c. 1640 with the celebration of (as it was supposed) the 200th anniversary of printing. Perhaps this use of the word traces to the title of the first catalog of such books, Incunabula typographiae (Amsterdam, 1688). The word in this sense has come into general use throughout Europe. The number of books put on the market throughout Europe during that period has been estimated at 20 million. Prof. Alfred W. Pollard ["Encyclopaedia Britannica," 1941] wrote that "up to the end of the 17th century," Caxton's original printings "could still be bought for a few shillings."

incur (v.)
c. 1400, "bring (an undesirable consequence) upon oneself;" mid-15c. as "become liable for (payment or expenses)," from Anglo-French encurir, Old French encorir "to run, flee; commit, contract, incur" (Modern French encourir), from Latin incurrere "run into or against, rush at, make an attack;" figuratively, "to befall, happen, occur to," from in- "upon" (from PIE root *en "in") + currere "to run" (from PIE root *kers- "to run"). Related: Incurred; incurring.
indeed (adv.)
c. 1600, a contraction into one word of the prepositional phrase in dede "in fact, in truth" (early 14c.), from Old English dæd "a doing, act, action, event" (see deed (n.)). As an interjection, 1590s; as an expression of surprise or disgust, 1834. Emphatic form yes (or no) indeedy attested from 1856, American English.
indent (v.1)
early 15c., indenten, endenten "to make notches; to give (something) a toothed or jagged appearance," also "to make a legal indenture, make a written formal agreement or contract," from Old French endenter "to notch or dent, give a serrated edge to" (12c.) and directly from Medieval Latin indentare "to furnish with teeth," from in- "into, in, on, upon" (from PIE root *en "in") + verb from Latin dens (genitive dentis) "tooth" (from PIE root *dent- "tooth").
An indented document was usually, if not always, written in two or more identical versions. Orig. these were written on a single sheet of parchment and then cut apart along a zigzag, or 'indented' line. Each party to the agreement retained one copy, which he could readily authenticate by matching its serrate edge with that of another copy. [Middle English Dictionary]
The printing sense "insert white space to force text inward" is first attested 1670s. Related: Indented (late 14c.); indenting.
indifferent (adj.)
late 14c., "unbiased, impartial, not preferring one to the other" (of persons), "alike, equal" (of things), from Old French indifferent "impartial" or directly from Latin indifferentem (nominative indifferens) "not differing, not particular, of no consequence, neither good nor evil," from in- "not, opposite of" (see in- (1)) + differens, present participle of differre "set apart" (see differ). Extended sense of "apathetic, no more inclined to one thing than to another" first recorded early 15c.; that of "neither good nor bad" is from 1530s, on notion of "neither more nor less advantageous," but since 17c. it has tended toward "rather bad."
indigenous (adj.)
"born or originating in a particular place," 1640s, from Late Latin indigenus "born in a country, native," from Latin indigena "sprung from the land, native," as a noun, "a native," literally "in-born," or "born in (a place)," from Old Latin indu (prep.) "in, within" + gignere (perfective genui) "to beget, produce," from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups. Indu "within" is from archaic endo, which is cognate with Greek endo- "in, within," from PIE *endo-, extended form of root *en "in." Related: Indigenously.
indurate (adj.)
"hardened, made hard," early 15c., from Latin induratus, past participle of indurare "to make hard, harden," from in- (from PIE root *en "in") + durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast."
indurate (v.)
1590s (transitive) "make hard;" 1620s (intransitive) "grow harder," from Latin induratus, past participle of indurare "to make hard, harden," from in- (from PIE root *en "in") + durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." Related: Indurated.
industry (n.)
late 15c., "cleverness, skill," from Old French industrie "activity; aptitude, experience" (14c.) or directly from Latin industria "diligence, activity, zeal," noun use of fem. of industrius "active, diligent," from early Latin indostruus "diligent," from indu "in, within" (from PIE *endo-, extended form of root *en "in") + stem of struere "to build" (from PIE root *stere- "to spread"). The meaning "habitual diligence, effort" is from 1530s; that of "systematic work" is from 1610s. The sense "a particular trade or manufacture" is first recorded 1560s.
ineffable (adj.)
late 14c., "beyond expression, too great for words, inexpressible," from Old French ineffable (14c.) or directly from Latin ineffabilis "unutterable," from in- "not, opposite of" (see in- (1)) + effabilis "speakable," from effari "utter," from assimilated form of ex "out" (see ex-) + fari "to say, speak," from PIE root *bha- (2) "to speak, tell, say." Meaning "that may not be spoken" is from 1590s. Plural noun ineffables was, for a time, a jocular euphemism for "trousers" (1823; see inexpressible). Related: Ineffably.
infamous (adj.)
a 16c. merger of two Middle English words, with the form of infamous "not well-known" (early 15c.) and the sense of infamis (late 14c.), "of ill repute, famous for badness." Infamous is from Medieval Latin infamosus, from in- "not, opposite of" (see in- (1)) + Latin famosus "celebrated" (see famous). Infamis is from Latin infamis "of ill fame" (see infamy). Meaning "causing infamy" is from 1550s. As a legal term, "disqualified from certain rights of citizens because of conviction for certain crimes" (late 14c.). The neutral fameless (in the sense original to infamous) is recorded from 1590s. Related: Infamously.
infamy (n.)
early 15c., "public disgrace, dishonor, evil fame," from Old French infamie "dishonor, infamous person" (14c.) and directly from Latin infamia "ill fame, bad repute, dishonor," from infamis "disreputable, notorious, of ill fame," from in- "not, without" (see in- (1)) + fama "reputation" (from PIE root *bha- (2) "to speak, tell, say"). Meaning "quality of being shamefully vile" is from 1510s. An earlier form in Middle English was infame (late 14c.), from Old French infame, an earlier form of infamie. Infame also was the Middle English verb in this set, "brand with infamy," from Old French infamer, from Latin infamare "bring into ill repute, defame," from infamis. The verb has become archaic in English (infamize is attested from 1590s).
infant (n.)
late 14c., infant, infaunt, "a child," also especially "child during earliest period of life, a newborn" (sometimes meaning a fetus), from Latin infantem (nominative infans) "young child, babe in arms," noun use of adjective meaning "not able to speak," from in- "not, opposite of" (see in- (1)) + fans, present participle of fari "to speak," from PIE root *bha- (2) "to speak, tell, say." As an adjective in English, 1580s, from the noun. The Romans extended the sense of Latin infans to include older children, hence French enfant "child," Italian fanciullo, fanciulla. In English the word formerly also had the wider sense of "child" (commonly reckoned as up to age 7). The common Germanic words for "child" (represented in English by bairn and child) also are sense extensions of words that originally must have meant "newborn."
infantile (adj.)
mid-15c., "pertaining to infants," from Late Latin infantilis "pertaining to an infant," from infans "young child" (see infant). Sense of "infant-like" is from 1772.
infantry (n.)
1570s, from French infantrie, infanterie (16c.), from older Italian or Spanish infanteria "foot soldiers, force composed of those too inexperienced or low in rank to be cavalry," a collective noun from infante "foot soldier," originally "a youth," from Latin infantem (see infant). Meaning "infants collectively" is recorded from 1610s. A Middle English (c. 1200) word for "foot-soldiers" was going-folc, literally "going-folk."
infect (v.)
late 14c., "fill with disease, render pestilential; pollute, contaminate; to corrupt morally," from Latin infectus, past participle of inficere "to stain, tinge, dye," also "to corrupt, stain, spoil," literally "to put in to, dip into," from in- "in" (from PIE root *en "in") + facere "to make, do, perform" (from PIE root *dhe- "to set, put"). In Middle English occasionally in a neutral sense "tinge, darken," but typically used of things indifferent or bad, and especially of disease. Related: Infected; infecting.
infelicity (n.)
late 14c., "unhappiness," from Latin infelicitas "bad luck, misfortune, unhappiness," from infelix (genitive infelicis) "unfruitful, barren; unfortunate, unhappy; causing misfortune, unlucky," from in- "not, opposite of" (see in- (1)) + felix "happy" (see felicity). Meaning "inappropriateness, unhappiness as to occasion" is from 1610s.
infer (v.)
in logic, "to 'bring in' as a conclusion of a process of reasoning," 1520s, from Latin inferre "bring into, carry in; deduce, infer, conclude, draw an inference; bring against," from in- "in" (from PIE root *en "in") + ferre "to carry, to bear," from PIE root *bher- (1) "to carry; to bear children." General sense of "draw a conclusion" is first attested 1520s; intransitive sense is from 1570s.
infidel (n.)
mid-15c., "adherent of a religion opposed to Christianity," from Middle French infidèle, from Latin infidelis "unfaithful, not to be trusted," in Late Latin "unbelieving" (in Medieval Latin also as a noun, "unbeliever"), from in- "not, opposite of" (see in- (1)) + fidelis "faithful" (from PIE root *bheidh- "to trust, confide, persuade"). Originally "a non-Christian" (especially a Saracen); later "one who does not believe in religion, disbeliever in religion generally" (1520s). Also used to translate Arabic qafir (see kaffir), which is from a root meaning "to disbelieve, to deny," strictly referring to all non-Muslims but virtually synonymous with "Christian;" hence, from a Muslim or Jewish point of view, "a Christian" (1530s). As an adjective from mid-15c., "of a religion opposed to Christianity;" 1520s as "rejecting the Christian religion while accepting no other."
infidelity (n.)
c. 1400, "want of faith, unbelief in religion; false belief, paganism;" also (early 15c.) "unfaithfulness or disloyalty to a person" (originally to a sovereign, by 16c. to a lover or spouse), from French infidélité (12c.) or directly from Latin infidelitatem (nominative infidelitas) "unfaithfulness, faithlessness," noun of quality from infidelis "unfaithful, unbelieving" (see infidel).
infirm (adj.)

late 14c., "weak, unsound" (of things), from Latin infirmus "weak, frail, feeble, not strong or firm" (figuratively "superstitious, pusillanimous, inconstant"), from in- "not, opposite of" (see in- (1)) + firmus "strong; stable," figuratively "constant, trusty" (from suffixed form of PIE root *dher- "to hold firmly, support" ). Of persons, "not strong, unhealthy," first recorded c. 1600. As a noun from 1711.

inflame (v.)
mid-14c., "make (someone) ardent; set (the spirit, etc.) on fire" with a passion or religious virtue, a figurative sense, from Old French enflamer "catch fire; set on fire" (Modern French enflammer), from Latin inflammare "to set on fire, kindle," figuratively "to rouse, excite," from in- "in" (from PIE root *en "in") + flammare "to flame," from flamma "a flame" (see flame (n.)). The literal sense of "to cause to burn" first recorded in English late 14c. Meaning "to heat, make hot, cause inflammation" is from 1520s. Formerly also enflame, but since 16c. the spelling with in- has predominated. Related: Inflamed; Inflaming.
inflammable (adj.)
"able to be set alight," c. 1600, from Middle French inflammable, from Medieval Latin inflammabilis, from Latin inflammare "to set on fire" (see inflame).Since 1980s use of the word, especially in safety warnings, has been sometimes discouraged for fear it could be misunderstood as meaning "non-flammable" through confusion of the two prefixes in-. The word was used earlier in medicine in the sense "liable to inflammation" (early 15c.). Related: Inflammability.
influence (v.)
1650s, from influence (n.). Related: Influenced; influencing.
influence (n.)
late 14c., an astrological term, "streaming ethereal power from the stars when in certain positions, acting upon character or destiny of men," from Old French influence "emanation from the stars that acts upon one's character and destiny" (13c.), also "a flow of water, a flowing in," from Medieval Latin influentia "a flowing in" (also used in the astrological sense), from Latin influentem (nominative influens), present participle of influere "to flow into, stream in, pour in," from in- "into, in, on, upon" (from PIE root *en "in") + fluere "to flow" (see fluent). The range of senses in Middle English were non-personal, in reference to any outflowing of energy that produces effect, of fluid or vaporous substance as well as immaterial or unobservable forces. Meaning "exertion of unseen influence by persons" is from 1580s (a sense already in Medieval Latin, for instance Aquinas); meaning "capacity for producing effects by insensible or invisible means" is from 1650s. Under the influence (of alcohol, etc.) "drunk" first attested 1866.
influenza (n.)
1743, borrowed (during an outbreak of the disease in Europe), from Italian influenza "influenza, epidemic," originally "visitation, influence (of the stars)," from Medieval Latin influentia in the astrological sense (see influence).
AN Article from Rome informs us that a Sort of Plague has broke out there, which destroys Abundance of their People, and they call it the Influenza. ["The Gentleman's Magazine," April 1743]
Used in Italian for diseases at least since 1504 (as in influenza di febbre scarlattina "scarlet fever") on notion of astral, occult, or atmospheric influence. The 1743 outbreak began in Italy. Often applied since mid-19c. to severe colds.
influx (n.)
1620s, from French influx (16c.) or directly from Late Latin influxus "a flowing in," from past participle stem of Latin influere "to flow in" (see influence (n.)). Originally of rivers, air, light, spiritual light, etc.; used of people from 1650s.
informatics (n.)
1967, translating Russian informatika (1966); see information + -ics.
infraction (n.)
mid-15c., "the breaking of an agreement," from Old French infraction (13c.) and directly from Latin infractionem (nominative infractio) "a breaking, weakening," noun of action from past participle stem of infringere "to damage, break off, break, bruise," from in- "in" (from PIE root *en "in") + frangere "to break" (from PIE root *bhreg- "to break"). The verb infract (1560s) is archaic.
infringe (v.)
mid-15c., enfrangen, "to violate," from Latin infringere "to damage, break off, break, bruise," from in- "in" (from PIE root *en "in") + frangere "to break" (from PIE root *bhreg- "to break"). Meaning "encroach" first recorded c. 1760. Related: Infringed; infringing.
ingenious (adj.)

early 15c., "intellectual, talented," from Middle French ingénieux "clever, ingenious" (Old French engeignos), from Latin ingeniosus "of good natural capacity, full of intellect, clever, gifted with genius," from ingenium "innate qualities, ability; inborn character," literally "that which is inborn," from in- "in" (from PIE root *en "in") + gignere, from PIE *gen(e)-yo-, suffixed form of root *gene- "give birth, beget."

Sense of "skillful, crafty, clever at contrivance" first recorded 1540s; earlier in this sense was Middle English enginous (mid-14c.), from Old French engeignos. Middle English also had engineful "skillful (in war)" (c. 1300). By a direct path, Latin ingenium produced Middle English ingeny "intellectual capacity, cleverness" (early 15c.), but this is obsolete. Compare engine. Related: Ingeniously; ingeniousness.

ingenuous (adj.)
1590s, "noble in nature, high-minded; honorably straightforward," from Latin ingenuus "with the virtues of freeborn people, of noble character, frank, upright, candid," originally "native, freeborn," literally "born in (a place)," from in- "in" (from PIE root *en "in") + PIE *gen(e)-wo-, suffixed form of root gene- "to give birth, beget, produce" (see genus). Sense of "artless, innocent" is 1670s, via evolution from "honorably open, straightforward," to "innocently frank." Related: Ingenuously; ingenuousness.
ingrate (n.)

"ungrateful person," 1670s, from earlier adjective meaning "unfriendly," also "ungrateful, unthankful" (14c.), from Latin ingratus "unpleasant, disagreeable," also "ungrateful, unthankful," and "thankless, unprofitable," from in- "not" (see in- (1)) + gratus "pleasing, beloved, dear, agreeable" (from suffixed form of PIE root *gwere- (2) "to favor").

ingratiate (v.)

1620s, possibly via 16c. Italian ingraziarsi "to bring (oneself) into favor," or an unrecorded Medieval Latin *ingratiatus, from Latin phrase in gratiam "for the favor of," from in "in" (from PIE root *en "in") + gratia "favor, grace" (from suffixed form of PIE root *gwere- (2) "to favor"). Related: Ingratiated; ingratiating.

ingredient (n.)

in early use also engredient, early 15c., "something forming part of a mixture," from Latin ingredientem (nominative ingrediens) "that which enters into" (a compound, recipe, etc.), present participle of ingredi "go in, enter," from in- "in" (from PIE root *en "in") + gradi "to step, go" (from PIE root *ghredh- "to walk, go"). Also from early 15c. as an adjective, "forming part of a mixture."

ingress (n.)

mid-15c., from Latin ingressus "an advance; walking; an entry," from ingress-, past participle stem of ingredi "to step into, enter," from in- "in" (from PIE root *en "in") + gradi "to step, go" (from PIE root *ghredh- "to walk, go"). The verb meaning "to enter, go in" sometimes said to be American English, but it is attested from early 14c.

inhabit (v.)
late 14c., from Old French enhabiter, enabiter "dwell in, live in, reside" (12c.), from Latin inhabitare "to dwell in," from in- "in" (from PIE root *en "in") + habitare "to dwell," frequentative of habere "to hold, have" (from PIE root *ghabh- "to give or receive"). Formerly also enhabit. Related: Inhabited; inhabiting.
inhibit (v.)
early 15c., "to forbid, prohibit," back-formation from inhibition or else from Latin inhibitus, past participle of inhibere "to hold in, hold back, keep back," from in- "in, on" (from PIE root *en "in") + habere "to hold" (from PIE root *ghabh- "to give or receive"). Psychological sense (1876) is from earlier, softened meaning of "restrain, check, hinder" (1530s). Related: Inhibited; inhibiting.
inhibition (n.)
late 14c., "formal prohibition; interdiction of legal proceedings by authority;" also, the document setting forth such a prohibition, from Old French inibicion and directly from Latin inhibitionem (nominative inhibitio) "a restraining," from past participle stem of inhibere "to hold in, hold back, keep back," from in- "in, on" (from PIE root *en "in") + habere "to hold" (from PIE root *ghabh- "to give or receive"). Psychological sense of "involuntary check on an expression of an impulse" is from 1876.
inhumation (n.)
"act of burying in the ground" (as opposed to cremation), 1630s, noun of action from inhume "to bury," literally "to put into the ground," from in- "in" (from PIE root *en "in") + humus "earth, soil" (see humus).
inhume (v.)
"bury, lay in the grave," c. 1600, from Latin inhumare "to bury," literally "to put into the ground," from in- "in" (from PIE root *en "in") + humus "earth, soil" (see humus). Related: Inhumed; inhuming.
initial (adj.)
1520s, "of or pertaining to a beginning," from Middle French initial or directly from Latin initialis "initial, incipient, of the beginning," from initium "a beginning, a commencement; an entrance, a going in," noun use of neuter past participle of inire "to go into, enter upon, begin," from in- "into, in" (from PIE root *en "in") + ire "to go" (from PIE root *ei- "to go"). Related: Initially.
initial (v.)
"to mark or sign with initials," 1837, from initial (n.). Related: Initialed; initialing.
initial (n.)
"initial letter of a name or surname," 1620s, from initial (adj.) in a specialized sense "standing at the beginning of a word, sentence, etc." (1620s).
initiate (n.)
"one who has been initiated" (in secret doctrines, etc.), 1732, from obsolete or archaic past-participle adjective initiate "initiated, instructed in secret knowledge" (c. 1600), from Latin initiatus (see initiate (v.)).
initiate (v.)
c. 1600, "introduce to some practice or system," also "begin, set going," from Late Latin initiatus, past participle of initiare "to begin, originate," in classical Latin only in the sense "to instruct in mysteries or sacred knowledge." This is from initium "a beginning; an entrance," also in plural initia "constituent parts; sacred mysteries," a noun use of the neuter past participle of inire "to go into, enter upon, begin," from in- "into, in" (from PIE root *en "in") + ire "to go" (from PIE root *ei- "to go"). In some senses the English word is a back-formation from initiation. Related: Initiated; initiates; initiating; initiator.
initiation (n.)
1580s, from Middle French initiation or directly from Latin initiationem (nominative initiatio) "participation in secret rites," noun of action from past participle stem of initiare "originate, initiate," from initium "a beginning" (see initial (adj.)).
injunction (n.)
early 15c., from Late Latin iniunctionem (nominative iniunctio) "a command," noun of action from past participle stem of Latin iniungere "impose, inflict, bring upon," literally "attach to," from in- "on" (from PIE root *en "in") + iungere "to join together," from nasalized form of PIE root *yeug- "to join."
innate (adj.)
early 15c., "existing from birth," from Late Latin innatus "inborn, native, natural" (source also of French inné, Spanish and Italian innato), past participle of innasci "to be born in, originate in," from in- "in" (from PIE root *en "in") + nasci "to be born" (Old Latin gnasci), from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups. Opposed to acquired. Related: Innately; innateness.
innumerable (adj.)
mid-14c., from Latin innumerabilis "countless, immeasurable," from in- "not" (see in- (1)) + numerabilis "able to be numbered," from numerare "to count, number," from numerus "a number" (see number (n.)). Related: Innumerability.
inoculate (v.)
mid-15c., "implant a bud into a plant," from Latin inoculatus, past participle of inoculare "graft in, implant a bud or eye of one plant into another," from in- "in" (from PIE root *en "in") + oculus "bud," originally "eye" (from PIE root *okw- "to see"). Meaning "implant germs of a disease to produce immunity" is from inoculation, originally in reference to smallpox, after 1799, often used in sense of "to inoculate with a vaccine." Related: Inoculated; inoculating.
inquiline (n.)
1640s, "a lodger," from Latin inquilinus "an inhabitant of a place not his own," from *incolinus, from incola "an inhabitant," from in- "in" (from PIE root *en "in") + colere "inhabit, dwell" (see colony). Zoological sense of "animal living in the abode of another, a commensal" is from 1865.
insect (n.)
c. 1600, from Latin (animal) insectum "(animal) with a notched or divided body," literally "cut into," noun use of neuter past participle of insectare "to cut into, to cut up," from in- "into" (from PIE root *en "in") + secare "to cut" (from PIE root *sek- "to cut"). The Latin word is Pliny's loan-translation of Greek entomon "insect" (see entomology), which was Aristotle's term for this class of life, in reference to their "notched" bodies. First in English in 1601 in Holland's translation of Pliny. In zoology, in reference to a class of animals, 1753. Translations of Aristotle's term also form the usual word for "insect" in Welsh (trychfil, from trychu "cut" + mil "animal"), Serbo-Croatian (zareznik, from rezati "cut"), Russian (nasekomoe, from sekat "cut"), etc. Insectarian "one who eats insects" is attested from 1893. Among the adjectival forms that have been tried in English (and mostly rejected by disuse) are insectile (1620s), insectic (1767), insective (1834), insectual (1849), insectine (1853), insecty (1859), insectan (1888).
insectivore (n.)
1863, from French insectivore (1817), from Latin insectivorus, from combining form of insectum (see insect) + vorare "devour, swallow" (from PIE root *gwora- "food, devouring").
insert (n.)
"something inserted," 1893, especially a paper, etc., placed in among the pages of a newspaper, magazine, etc., from insert (v.).
insert (v.)

"to set in, put or place in," 1520s, from Latin insertus, past participle of inserere "to graft, implant," from in- "in" (from PIE root *en "in") + serere "join together, arrange, put in a row," from PIE root *ser- (2) "to line up." Middle English had inseren "to set in place, to graft, to introduce (into the mind)" (late 14c.), directly from the Latin verb. Related: Inserted; inserting.

inset (n.)
1550s, "influx of water; place where water flows in," from in (prep.) + set (n.2). The sense "that which is set in" ("extra pages of a book, etc.," 1871; "small map in the border of a larger one," 1872) probably is a separate formation. In Old English insetan (Old Northumbrian insetta) meant "an institution," literally "a setting in," and perhaps a loan-translation of the source of institution. Similar formation in German einsetzen "to use, employ; institute, begin; install."
insidious (adj.)
1540s, from Middle French insidieux "insidious" (15c.) or directly from Latin insidiosus "deceitful, cunning, artful, treacherous," from insidiae (plural) "plot, snare, ambush," from insidere "sit on, occupy," from in- "in" (from PIE root *en "in") + sedere "to sit," from PIE root *sed- (1) "to sit." Figurative, usually with a suggestion of lying in wait and the intent to entrap. Related: Insidiously; insidiousness.
insignia (n.)
1640s, from Latin insignia, neuter plural of insigne "badge of honor or office, mark, proof, sign, token," from in- "in" (from PIE root *en "in") + signum "identifying mark, sign" (see sign (n.)). The classically correct singular is insigne.
insist (v.)
1580s, from French insister (14c.) or directly from Latin insistere "take a stand, stand on, stand still; follow, pursue; insist, press vigorously, urge, dwell upon," from in- "upon" (from PIE root *en "in") + sistere "take a stand," from PIE *si-st-, reduplicated form of root *sta- "to stand, make or be firm." Perhaps in some cases a back-formation from insistence. Related: Insisted; insisting.
insolate (v.)
"expose to the rays of the sun," 1620s, from Latin insolatus, past participle of insolare "place in the sun, expose to the sun," from in- "in" (from PIE root *en "in") + sol "sun" (from PIE root *sawel- "the sun"). Related: Insolated; insolating.
insolation (n.)
"exposure to the sun's rays," 1610s, from French insolation (16c.), from Latin insolationem (nominative insolatio), noun of action from past participle stem of insolare "place in the sun, expose to the sun," from in- "in" (from PIE root *en "in") + sol "sun" (from PIE root *sawel- "the sun").
insolent (adj.)
late 14c., "contemptuous, arrogant, showing haughty disregard of others," from Latin insolentem (nominative insolens) "arrogant, immoderate," also "unaccustomed, unwonted," literally "unusual, unfamiliar," from in- "not, opposite of" (see in- (1)) + solentem, present participle of solere "be accustomed, be used to; cohabit with," from Proto-Italic *sol-e-. This is of uncertain origin. An old guess connects it to the source of Latin sodalis "close companion," and suescere "become used to," but de Vaan rejects this on phonetic grounds. Another guess connects it to the source of Latin solum "ground," with a possible sense shift from "inhabit" to "be accustomed to." Or it might be from PIE root *sel- (1) "human settlement" (source also of Old Church Slavonic selo "courtyard, village," Russian selo "village," Old English sele, Old High German sal "hall, house"). Meaning "contemptuous of rightful authority" is from 1670s. Related: Insolently.
Insolent is now chiefly used of language that is intentionally and grossly rude, defiant, or rebellious. Where it applies to conduct, the conduct includes language as the most offensive thing. [Century Dictionary, 1902]
insomnia (n.)
"chronic inability to sleep," 1620s, insomnie, from Latin insomnia "want of sleep, sleeplessness," from insomnis "sleepless," from in- "not" (see in- (1)) + somnus "sleep" (from PIE root *swep- "to sleep"). The re-Latinized form is from 1758.
instant (n.)
late 14c., "moment in time, infinitely short space of time," from noun use of Old French instant "near, immediate, at hand; assiduous, urgent" (see instant (adj.)). Related: Instanted; instanting.
instant (adj.)
mid-15c., "now, present, of the moment, current," from Old French instant "near, imminent, immediate, at hand; urgent, assiduous" (14c.) and directly from Medieval Latin instantem (nominative instans), in classical Latin "present, pressing, urgent," literally "standing near," present participle of instare "to urge, to stand near, be present (to urge one's case)," from in- "in" (from PIE root *en "in") + stare "to stand," from PIE root *sta- "to stand, make or be firm." Sense of "immediate, done or occurring at once" is from 1590s. Of processed foods, by 1912; instant coffee is from 1915. Televised sports instant replay attested by 1965. Instant messaging attested by 1994. The word was used 18c.-19c. in dating of correspondence, meaning "the current month," often abbreviated inst. Thus 16th inst. means "sixteenth of the current month" (see ultimo).
instauration (n.)
"restoration, renewal," c. 1600, from Latin instaurationem (nominative instauratio) "a renewal," noun of action from past participle stem of instaurare "to set up, establish; renew, restore," from in- "in" (from PIE root *en "in") + -staurare (ending also found in restaurant), from PIE *stauro-, from root *sta- "to stand, make or be firm."
instellation (n.)
"a putting among the stars," 1795, from in- (2) "in" + noun of action from Latin stellare "to set with stars," from stella (from PIE root *ster- (2) "star"). Perhaps modeled on earlier French instellation.
institute (v.)
early 14c., "to establish in office, appoint," from Latin institutus, past participle of instituere "to set up, put in place; arrange; found, establish; appoint, designate; govern, administer; teach, instruct," from in- "in" (from PIE root *en "in") + statuere "establish, to cause to stand," from PIE root *sta- "to stand, make or be firm." General sense of "set up, found, introduce" first attested late 15c. Related: Instituted; instituting.
institute (n.)
1510s, "purpose, design," from Latin institutum "an ordinance; a purpose; a custom; precedents; principal components," literally "thing set up," noun use of neuter past participle of instituere "to set up, put in place; arrange; found, establish" (see institute (v.)). From 1540s in English as "an established law." The sense of "an organization or society devoted to some specific work," especially literary or scientific, is from 1828, from French use in Institut national des Sciences et des Arts (established 1795); Dutch instituut, German Institut also are from French. The specialized (mostly U.S.) sense "traveling academy for teachers in a district" is from 1839.
A "Teachers' Institute" is a meeting composed of teachers of Common Schools, assembled for the purpose of improvement in the studies they are to teach, and in the principles by which they are to govern. It is the design of a Teachers' Institute to bring together those who are actually engaged in teaching Common Schools, or who propose to become so, in order that they may be formed into classes and that these classes, under able instructers, may be exercised, questioned and drilled, in the same manner that the classes of a good Common School are exercised, questioned and drilled. [Horace Mann, secretary's report to the Boston Board of Education, Sept. 1, 1845]
instruct (v.)
early 15c., "to tell, inform, impart knowledge or information," also "furnish with authoritative directions," from Latin instructus, past participle of instruere "arrange, prepare, set in order; inform, teach," literally "to build, erect," from in- "on" (from PIE root *en "in") + struere "to pile, build" (from PIE *streu-, extended form of root *stere- "to spread"). Related: Instructed; instructing.
instruction (n.)
c. 1400, instruccioun, "action or process of teaching," from Old French instruccion (14c., Modern French instruction), from Latin instructionem (nominative instructio) "an array, arrangement," in Late Latin "teaching," from past participle stem of instruere "arrange, prepare, set in order; inform, teach," from in- "on" (from PIE root *en "in") + struere "to pile, build" (from PIE *streu-, extended form of root *stere- "to spread").
Teaching is the general word for the imparting of knowledge .... Instruction has the imparting of knowledge for its object, but emphasizes, more than teaching, the employment of orderly arrangement in the things taught. [Century Dictionary]
Meaning "an authoritative direction telling someone what to do; a document giving such directions," is early 15c. Related: Instructions.
instrument (n.)
late 13c., "musical instrument, mechanical apparatus for producing musical sounds," from Old French instrument, enstrument "means, device; musical instrument" (14c., earlier estrument, 13c.) and directly from Latin instrumentum "a tool, an implement; means, furtherance; apparatus, furniture; ornament, dress, embellishment; a commission, authorization; a document," from instruere "arrange, prepare, set in order; inform, teach," literally "to build, erect," from in- "on" (from PIE root *en "in") + struere "to pile, build" (from PIE *streu-, extended form of root *stere- "to spread"). The word in other Germanic languages also is from French. In English the meaning "a means, an agency" is from mid-14c. The sense of "hand-tool, implement, utensil, something used to produce a mechanical effect" is from early 14c. "Now usually distinguished from a tool, as being used for more delicate work or for artistic or scientific purposes" [OED]. The legal meaning "written document by which formal expression is given to a legal act" is from early 15c. Formerly also used of body parts or organs with special functions.
In wyfhode I wol vse myn Instrument As frely as my makere hath it sent. [Chaucer, "Wife of Bath's Prologue"]
integument (n.)
1610s, from Latin integumentum "a covering," from integere "to cover over," from in- "in, upon" (from PIE root *en "in") + tegere "to cover," from PIE root *(s)teg- "to cover." Specific sense in biology is from 1660s.
intelligence (n.)
late 14c., "the highest faculty of the mind, capacity for comprehending general truths;" c. 1400, "faculty of understanding, comprehension," from Old French intelligence (12c.) and directly from Latin intelligentia, intellegentia "understanding, knowledge, power of discerning; art, skill, taste," from intelligentem (nominative intelligens) "discerning, appreciative," present participle of intelligere "to understand, comprehend, come to know," from assimilated form of inter "between" (see inter-) + legere "choose, pick out, read," from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')." Meaning "superior understanding, sagacity, quality of being intelligent" is from early 15c. Sense of "information received or imparted, news" first recorded mid-15c., especially "secret information from spies" (1580s). Meaning "a being endowed with understanding or intelligence" is late 14c. Intelligence quotient first recorded 1921 (see I.Q.).
intelligentsia (n.)
"the intellectual class collectively," 1905, from Russian intelligyentsiya, from Latin intelligentia "intelligence" (see intelligence). Perhaps via Italian intelligenzia.
intend (v.)
c. 1300, entenden, "direct one's attention to, pay attention, give heed," from Old French entendre, intendre "to direct one's attention" (in Modern French principally "to hear"), from Latin intendere "turn one's attention, strain (in quest of something), be zealous," literally "stretch out, extend," from in- "toward" (from PIE root *en "in") + tendere "to stretch," from PIE root *ten- "to stretch." Sense of "have as a plan, have in mind or purpose" (late 14c.) was present in Latin. A Germanic word for this was ettle, from Old Norse ætla "to think, conjecture, propose," from Proto-Germanic *ahta "consideration, attention" (source also of Old English eaht, German acht). Related: Intended; intending.
intercalate (v.)
"to insert a day into the calendar," 1610s, from Latin intercalatus, past participle of intercalare "to proclaim the insertion of an intercalary day," from inter "between" (see inter-) + calare "to call" (an intercalary day; see calendar). Sometimes used in a general sense, "to insert between others" (1824). Related: Intercalated; intercalating. A necessary process in the Roman calendar to balance the solar and lunar aspects of it. Intercalation was done after Feb. 23 or 24 (the terminalia), every two or four years. Twenty-seven days were intercalated, making a full intercalary month (which included the last four or five days of Februarius), known as mensis intercalaris (and also known, according to Plutarch, as Mercedonius). No one now knows why the intercalation was done in the middle of February rather than after its end, unless it was because the important festivals at the end of that month (Regifugium and Equirra) were closely associated with holidays in early March. After Caesar's reform (46 B.C.E.) the only intercalary day is Feb. 29 every four years.
intercede (v.)
1570s, "to come between in space or time" (obsolete); c. 1600, "to interpose on behalf of another," a back-formation from intercession, or else from Latin intercedere "intervene, come between, be between" (in Medieval Latin "to interpose on someone's behalf"), from inter "between" (see inter-) + cedere "to go" (from PIE root *ked- "to go, yield"). Related: Interceded; interceding.
intercourse (n.)
mid-15c., "communication to and fro," ("In early use exclusively with reference to trade" [OED]), from Old French entrecors "exchange, commerce, communication" (12c., Modern French entrecours), from Late Latin intercursus "a running between, intervention," in Medieval Latin "intercommunication," from intercursus, past participle of intercurrere "to run between, intervene, mediate," from Latin inter "between" (see inter-) + currere "to run" (from PIE root *kers- "to run"). Sense of "frequent and habitual meeting and contact, social communication between persons" is from 1540s. Meaning "mental or spiritual exchange or intercommunication" is from 1560s. Meaning "sexual relations" (1798) probably is a shortening of euphemistic sexual intercourse (1771) with intercourse in its sense "social contact and relations."
interest (v.)
"cause to be interested, engage the attention of," c. 1600, earlier interesse (1560s), from the noun (see interest (n.)). Perhaps also from or influenced by interess'd, past participle of interesse.
interest (n.)
mid-15c., "legal claim or right; a concern; a benefit, advantage, a being concerned or affected (advantageously)," from Old French interest "damage, loss, harm" (Modern French intérêt), from noun use of Latin interest "it is of importance, it makes a difference," third person singular present of interresse "to concern, make a difference, be of importance," literally "to be between," from inter "between" (see inter-) + esse "to be" (from PIE root *es- "to be"). The sense development to "profit, advantage" in French and English is not entirely clear. The earlier Middle English word was interesse (late 14c.), from Anglo-French interesse "what one has a legal concern in," from Medieval Latin interesse "compensation for loss," noun use of Latin interresse (compare German Interesse, from the same Medieval Latin source). Financial sense of "money paid for the use of money lent" (1520s) earlier was distinguished from usury (illegal under Church law) by being in reference to "compensation due from a defaulting debtor." Sense of "personal or selfish consideration" is from 1620s. Meaning "business in which several people are interested" is from 1670s. Meaning "curiosity, feeling that something concerns one, appreciative or sympathetic regard" is first attested 1771. Interest group is attested from 1907; interest rate by 1868.
interfere (v.)
formerly also enterfere, mid-15c., "to strike against," from Middle French enterferir "exchange blows, strike each other," from entre- "between" (see entre-) + ferir "to strike," from Latin ferire "to knock, strike," related to Latin forare "to bore, pierce" (from PIE root *bhorh- "hole"). Compare punch (v.), which has both the senses "to hit" and "to make a hole in"). Figurative sense of "to meddle with, oppose unrightfully" is from 1630s. Related: Interfered; interfering. Modern French interférer is from English.
interlocution (n.)
"interchange of speech, dialogue, action of talking and replying," 1530s, from Latin interlocutionem (nominative interlocutio) "a speaking between, interlocution," noun of action from past participle stem of interloqui "to speak between; to interrupt," from inter "between" (see inter-) + loqui "to speak" (from PIE root *tolkw- "to speak").
interlocutor (n.)
1510s, "one who speaks in a dialogue or conversation," agent noun from Latin interlocut-, past participle stem of interloqui "speak between; interrupt," from inter "between" (see inter-) + loqui "to speak" (from PIE root *tolkw- "to speak"). In minstrel shows, the name of a straight-man character (1870) who was the questioner of the end men. Related: Interlocutory. Fem. forms include interlocutress (1858), interlocutrix (1846), interlocutrice (1848).
intermediate (v.)
c. 1600, "to interfere;" 1620s, "to mediate," from inter- "between" + mediate (v.). Related: Intermediated; intermediating.
intermediate (adj.)
"being or occurring between" (two things), early 15c., from Medieval Latin intermediatus "lying between," from Latin intermedius "that which is between," from inter "between" (see inter-) + medius "in the middle" (from PIE root *medhyo- "middle").
internal (adj.)
early 15c., "extending toward the interior," from Medieval Latin internalis, from Latin internus "within, inward, internal," figuratively "domestic," expanded from pre-Latin *interos, *interus "on the inside, inward," from PIE *en-ter- (source also of Old Church Slavonic anter, Sanskrit antar "within, between," Old High German unter "between," and the "down" sense of Old English under); suffixed (comparative) form of root *en "in." Meaning "situated within" is from 1590s. Meaning "of or pertaining to the domestic affairs of a country (as in internal revenue) is from 1795; the notion is "pertaining to the subject itself; independent of others." Internal-combustion in reference to an engine in which fuel is burned inside it, is from 1884. Related: Internally.
interpellation (n.)
late 15c., "an appeal" (obsolete), from Latin interpellationem (nominative interpellatio) "an interruption," noun of action from past participle stem of interpellare "to interrupt by speaking," from inter "between" (see inter-) + pellare, collateral form of pellere "to drive" (from PIE root *pel- (5) "to thrust, strike, drive"). The parliamentary sense is attested in English from 1837, from French.
interpolate (v.)
1610s, "to alter or enlarge (a writing) by inserting new material," from Latin interpolatus, past participle of interpolare "alter, freshen up, polish;" of writing, "falsify," from inter "among, between" (see inter-) + polare, which is related to polire "to smoothe, polish," from PIE root *pel- (5) "to thrust, strike, drive," the connecting notion being "to full cloth" [Watkins]. Sense evolved in Latin from "refurbish," to "alter appearance of," to "falsify (especially by adding new material)." Middle English had interpolen (early 15c.) in a similar sense. Related: Interpolated; interpolating.
interpret (v.)

late 14c., "expound the meaning of, render clear or explicit," from Old French interpreter "explain; translate" (13c.) and directly from Latin interpretari "explain, expound, understand," from interpres "agent, translator," from inter "between" (see inter-) + second element probably from PIE *per- (5) "to traffic in, sell." Related: Interpreted; interpreting.

interregnum (n.)
1580s, from Latin interregnum "an interval between two reigns," literally "between-reign," from inter "between" (see inter-) + regnum "kingship, dominion, rule, realm," related to regere "to rule, to direct, keep straight, guide" (from PIE root *reg- "move in a straight line," with derivatives meaning "to direct in a straight line," thus "to lead, rule"). In the republic, it meant a vacancy in the consulate. The earlier English noun was interreign (1530s), from French interrègne (14c.).
interrogate (v.)
late 15c., a back-formation from interrogation or else from Latin interrogatus, past participle of interrogare "to ask, question, inquire; interrogate judicially, cross-examine," from inter "between" (see inter-) + rogare "to ask, to question," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line." The Old French word was interroger (14c.) which yielded English interroge (late 15c.), now obsolete. Related: Interrogated; interrogating.
interrogation (n.)
late 14c., "a question;" c. 1500, "a questioning; a set of questions," from Old French interrogacion "a questioning" (13c.) or directly from Latin interrogationem (nominative interrogatio) "a question; questioning; judicial inquiry," noun of action from past participle stem of interrogare "to ask, question, inquire; interrogate judicially, cross-examine," from inter "between" (see inter-) + rogare "to ask, to question," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line."
interrogative (adj.)
"asking or denoting a question," c. 1500, from Late Latin interrogativus "pertaining to a question," from interrogat-, past participle stem of Latin interrogare "to ask, question, inquire; interrogate judicially, cross-examine," from inter "between" (see inter-) + rogare "to ask, to question," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line." As a noun, "word implying a question," 1520s. Related: Interrogatively.
interrogatory (adj.)
"containing or expressing a question," 1570s, from Late Latin interrogatorius "consisting of questions," from past participle stem of Latin interrogare "to ask, question, inquire; interrogate judicially, cross-examine," from inter "between" (see inter-) + rogare "to ask, to question," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line."
intersect (n.)
"point of intersection," 1850, from intersect (v.) or from Latin intersectum, neuter past pasticiple of intersecare. Earlier (1650s) it was used for "an insect."
intersect (v.)
1610s (trans.), back-formation from intersection, or else from Latin intersectus, past participle of intersecare "intersect, cut asunder," from inter "between" (see inter-) + secare "to cut" (from PIE root *sek- "to cut"). Intransitive sense is from 1847. Related: Intersected; intersecting.
intersection (n.)
1550s, "act or fact of crossing," from Middle French intersection (14c.) and directly from Latin intersectionem (nominative intersectio) "a cutting asunder, intersection," noun of action from past participle stem of intersecare "intersect, cut asunder," from inter- "between" (see inter-) + secare "to cut" (from PIE root *sek- "to cut"). In English originally a term in geometry; meaning "crossroads, a place of crossing" is from 1864. Related: Intersectional.
interstellar (adj.)
1620s, "situated between or among the stars," in reference to the night sky (modern astronomical sense is from 1670s), from inter- "between" + Latin stella "star" (from PIE root *ster- (2) "star"). Intersiderial in the same sense is from 1650s.
interstice (n.)
early 15c., from Old French interstice (14c.) and directly from Latin interstitium "interval," literally "space between," from inter "between" (see inter-) + stem of stare "to stand," from PIE root *sta- "to stand, make or be firm." Related: Interstices.
intervene (v.)
1580s, "intercept" (obsolete), a back-formation from intervention, or else from Latin intervenire "to come between, intervene; interrupt; stand in the way, oppose, hinder," from inter "between" (see inter-) + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Sense of "come between, fall or happen between" (of events) is from c. 1600; that of "interfere, interpose oneself between, act mediatorially" is from 1640s. Related: Intervened; intervener; intervening.
intervenient (adj.)
c. 1600, from Latin intervenientem (nominative interveniens), present participle of intervenire "to come between, interrupt," from inter "between" (see inter-) + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Related: Interveniently.
intervent (v.)
"to come between" (obsolete), 1590s, from Latin interventus, past participle of intervenire "to come between, interrupt," from inter- "between" (see inter-) + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Related: Intervented; interventing.
intervention (n.)
early 15c., "intercession, intercessory prayer," from Middle French intervention or directly from Late Latin interventionem (nominative interventio) "an interposing, a giving security," literally "a coming between," noun of action from past participle stem of Latin intervenire "to come between, interrupt," from inter "between" (see inter-) + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Later "act of intervening" in any way; in 19c.-20c. often of international relations; by 1983 of interpersonal intrusions by friends or family meant to reform a life felt to be going wrong.
interview (v.)
in early use also enterview, enterveu, 1540s, "to have a personal meeting," from interview (n.). Meaning "have an interview with" (usually with intent to publish what is said" is from 1869. Related: Interviewed; interviewing.
interview (n.)
1510s, "face-to-face meeting, formal conference," from Middle French entrevue, verbal noun from s'entrevoir "to see each other, visit each other briefly, have a glimpse of," from entre- "between" (see inter-) + Old French voir "to see" (from Latin videre, from PIE root *weid- "to see"). Modern French interview is from English. Journalistic sense "conversation with someone to obtain statements for publication" is from 1869 in American English.
The 'interview,' as at present managed, is generally the joint product of some humbug of a hack politician and another humbug of a newspaper reporter. ["The Nation," Jan. 28, 1869]
Meaning "personal meeting to discuss hiring or employment" is by 1921; earlier it was used in military recruiting (1918).
intimate (adj.)
1630s, "closely acquainted, very familiar," also "inmost, intrinsic," from Late Latin intimatus, past participle of intimare "make known, announce, impress," from Latin intimus "inmost, innermost, deepest" (adj.), also used figuratively, of affections, feelings, as a noun, "close friend;" superlative of in "in" (from PIE root *en "in"). Intimate (adj.) used euphemistically in reference to women's underwear from 1904. Related: Intimately.
intone (v.2)
obsolete 17c.-18c. verb, from French entoner "thunder, roar, resound, reverberate," from Latin intonare "to thunder, resound," figuratively "to cry out vehemently," from tonare "to thunder" (see thunder (n.)). Related: Intoned; intoning.
intone (v.1)
late 14c., entunen "sing, chant, recite, vocalize," from Old French entoner "to sing, chant" (13c.), from Medieval Latin intonare "sing according to tone," from Latin in- "in" (from PIE root *en "in") + tonus "tone," from Greek tonos, from PIE root *ten- "to stretch." Related: Intoned; intoning.
intrinsic (adj.)
late 15c., "interior, inward, internal," from Middle French intrinsèque "inner" (14c.), from Medieval Latin intrinsecus "interior, internal," from Latin intrinsecus (adv.) "inwardly, on the inside," from intra "within" (see intra-) + secus "along, alongside," from PIE *sekw-os- "following," suffixed form of root *sekw- (1) "to follow." The form in English was conformed to words in -ic by 18c. Meaning "belonging to the nature of a thing" is from 1640s. Related: Intrinsical; intrinsically.
introit (n.)
in liturgics, "an antiphon sung as the priest approaches the altar to celebrate mass," late 15c., from Old French introite "(liturgical) introit; entrance" (14c.), from Latin (antiphona ad) introitum, from introitus "a going in, an entering, entrance; a beginning, prelude," past participle of introire "to enter," from intro- "on the inside, within" (see intro-) + ire "to go" (from PIE root *ei- "to go").
introrse (adj.)
"turned or facing inward," 1831 (earlier in French), from Latin introrsus (adv.) "toward the inside," a contraction of introversus, from intro "within" (see intro-) + versus "turned," past participle of vertere "to turn," from PIE root *wer- (2) "to turn, bend."
introvert (n.)
1878, in zoology, "part or organ which is turned in upon itself," from introvert (v.). The psychological sense "introverted person" (opposed to extrovert) is 1917, from German, introduced there by C.G. Jung (1875-1961).
introvert (v.)
1650s, from Latin intro "inward, within" (see intro-) + vertere "to turn" (from PIE root *wer- (2) "to turn, bend").
intumescence (n.)
"swollen state, expansion," 1650s, from French intumescence (17c.), from Latin intumescere "to swell up, rise, be elevated," of sounds, "grow louder," figuratively, "grow excited, become enraged," from in- "in" (from PIE root *en "in") + tumescere "begin to swell, swell up," figuratively "grow excited, become enraged," inceptive of tumere "to swell" (from PIE root *teue- "to swell"), with inchoative suffix -escere.
intumescent (adj.)
"swelling up," 1796, from Latin intumescentem (nominative intumescens), present participle of intumescere "to swell up, rise, be elevated," of sounds, "grow louder," figuratively, "grow excited, become enraged," from in- "in" (from PIE root *en "in") + tumescere "begin to swell, swell up," figuratively "grow excited, become enraged," inceptive of tumere "to swell" (from PIE root *teue- "to swell"), with inchoative suffix -escere.
inundate (v.)
1620s, back-formation from inundation, or else from Latin inundatus, past participle of inundare "to overflow, run over" (source also of Spanish inundar, French inonder). Related: Inundated; inundating.
inundation (n.)
early 15c., from Latin inundationem (nominative inundatio) "an overflowing," noun of action from past participle stem of inundare "to overflow," from in- "onto" (from PIE root *en "in") + undare "to flow," from unda "a wave," from PIE *unda-, nasalized form of root *wed- (1) "water; wet."
invalid (n.)
"infirm or sickly person," 1709, originally of disabled military men, from invalid (adj.1). In Paris, Invalides is short for Hôtel des Invalides, home for old and disabled soldiers in the 7th arrondissement of Paris.
invalid (adj.2)
"of no legal force," 1630s, from special use of Latin invalidus "not strong, infirm, impotent, feeble, inadequate," from in- "not" (see in- (1)) + validus "strong" (from PIE root *wal- "to be strong").
invalid (adj.1)
"not strong, infirm," also "infirm from sickness, disease, or injury", 1640s, from Latin invalidus "not strong, infirm, impotent, feeble, inadequate," from in- "not" (see in- (1)) + validus "strong" (from PIE root *wal- "to be strong"). With pronunciation from French invalide (16c.).
invective (n.)

"an attacking in words," 1520s, from Medieval Latin invectiva "abusive speech," from Late Latin invectivus "abusive, scolding" from invect-, past participle stem of invehere "to bring in, carry in, introduce," also "assault, assail," from in- "against" (see in- (1)) + vehere "to carry" (from PIE root *wegh- "to go, move, transport in a vehicle"). For nuances of usage, see humor (n.). The earlier noun form in English was inveccion (mid-15c.), and invective (adj.) was in Middle English.

inveigh (v.)

formerly also enveigh, late 15c., "to introduce," from Latin invehere "to bring in, carry in, introduce," also "assault, assail," from in- "against" (see in- (1)) + vehere "to carry" (from PIE root *wegh- "to go, move, transport in a vehicle"). Meaning "to give vent to violent denunciation" is from 1520s, from a secondary sense in Latin (see invective). Related: Inveighed; inveighing.

inveigle (v.)
formerly also enveigle, etc., late 15c., "to blind (someone's) judgment," apparently an alteration of Middle French aveugler "delude, make blind," from Vulgar Latin *aboculus "without sight, blind," from Latin ab- "off, away from" (see ab-) + oculus "eye" (from PIE root *okw- "to see"). The Latin word is a loan-translation of Greek ap ommaton "without eyes." Meaning "to win over by deceit, seduce" is 1530s. Related: Inveigler; inveiglment.
invent (v.)
c. 1500, "to find, discover" (obsolete), a back-formation from invention or else from Latin inventus, past participle of invenire "to come upon; devise, discover." General sense of "make up, fabricate, concoct, devise" (a plot, excuse, etc.) is from 1530s, as is that of "produce by original thought, find out by original study or contrivance." Related: Invented; inventing.
invention (n.)
early 15c., "finding or discovering of something," from Old French invencion (13c.) and directly from Latin inventionem (nominative inventio) "faculty of invention," noun of action from past participle stem of invenire "to come upon, find; find out; invent, discover, devise; ascertain; acquire, get earn," from in- "in, on" (from PIE root *en "in") + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Sense of "thing invented" is first recorded 1510s; that of "act or process of finding out how to make or do" is from 1530s.
Invention is applied to the contrivance and production of something, often mechanical, that did not before exist, for the utilization of powers of nature long known or lately discovered by investigation. Discovery brings to light what existed before, but was not known. [Century Dictionary]
Earliest sense of the word in Middle English was "devised method of organization" (c. 1400), now obsolete. Meaning "finding or discovery of something" is preserved in Invention of the Cross, Church festival (May 3) celebrating the reputed finding of the Cross of the Crucifixion by Helena, mother of Constantine, in 326 C.E. The related classical Latin word for "a device, contrivance" was inventum.
inventor (n.)
c. 1500, "a discoverer, one who finds out" (now obsolete), from Latin inventor (fem. inventrix, source of French inventeur (15c.), Spanish inventor, Italian inventore) "contriver, author, discoverer, proposer, founder," agent noun from past participle stem of invenire "to come upon, find; find out; invent, discover, devise; ascertain; acquire, get earn," from in- "in, on" (from PIE root *en "in") + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Meaning "one who contrives or produces a new thing or process" is from 1550s.
inventory (n.)
early 15c., from Old French inventoire "detailed list of goods, a catalogue" (15c., Modern French inventaire), from Medieval Latin inventorium, alteration of Late Latin inventarium "list of what is found," from Latin inventus, past participle of invenire "to find, discover, ascertain" (see invention). The form was altered in Medieval Latin by influence of words in -orium, which became very common in post-classical and Christian use. It properly belongs with words in -ary, and French has corrected the spelling. Related: Inventorial; inventorially.
inventory (v.)
"make a list or catalogue of," c. 1600, from inventory (n.). Related: Inventoried; inventorying.
Inverness
literally "mouth of the (River) Ness (probably from an Old Celtic word meaning "roaring one"), from Inver-, element in place names in Scotland of Gaelic origin, usually of places at the confluence of a river with another or the sea, from Old Irish *in(d)ber- "estuary," literally "a carrying in," from Celtic *endo-ber-o-, from *endo- "in" (from PIE *en-do-, extended form of root *en; see in) + from *ber- "to carry," from PIE root *bher- (1) "to carry," also "to bear children."
invert (v.)
"to turn (something) in an opposite direction; reverse the position, order, or sequence of," 1530s, from Middle French invertir or directly from Latin invertere "turn upside down, turn about; upset, reverse, transpose," figuratively "pervert, corrupt, misrepresent," of words, "to use ironically," from in- "in, on" (from PIE root *en "in") + vertere "to turn" (from PIE root *wer- (2) "to turn, bend"). Related: Inverted; inverting; invertedly.
invictus

Latin adjective, "unconquered, unsubdued, invincible," from in- "not, opposite of" (see in- (1)) + victus, past participle of vincere "to conquer, overcome" (from nasalized form of PIE root *weik- (3) "to fight, conquer").

It matters not how strait the gate,
How charged with punishments the scroll,
I am the master of my fate,
I am the captain of my soul.
[William Ernest Henley, "Invictus"]
invidious (adj.)
c. 1600, from Latin invidiosus "full of envy, envious" (also "exciting hatred, hateful"), from invidia "envy, grudge, jealousy, ill will" (see envy (n.)). Envious is the same word, but passed through French. Related: Invidiously; invidiousness.
invincible (adj.)

early 15c., from Old French invincible (14c.) or directly from Latin invincibilis "unconquerable," from in- "not" (see in- (1)) + vincibilis "to be gained, easily maintained, conquerable," from vincere "to overcome" (from nasalized form of PIE root *weik- (3) "to fight, conquer"). Related: Invincibly.

The noun meaning "one who is invincible" is from 1630s. Invincible ignorance, an ignorance which the person having it lacks means to overcome, is from Church Latin ignorantia invincibilis (Aquinas). The Invincible Armada was the Spanish of 1588. Related: Invincibly.

invoice (n.)
"written account of the particulars and prices of merchandise shipped or sent," 1550s, apparently from a re-Latinized form of Middle French envois, plural of envoi "dispatch (of goods)," literally "a sending," from envoyer "to send," from Vulgar Latin *inviare "send on one's way," from Latin in "on" (from PIE root *en "in") + via "road" (see via (adv.)). As a verb, 1690s, from the noun.
involve (v.)

late 14c., "envelop, surround; make cloudy or obscure," from Old French involver and directly from Latin involvere "envelop, surround, overwhelm," literally "roll into," from in- "in" (from PIE root *en "in") + volvere "to roll," from PIE root *wel- (3) "to turn, revolve." Mid-15c. as "concern oneself." Sense of "take in, include" first recorded c. 1600. Related: Involved; Involving.

Obscurest night involved the sky,
The Atlantic billows roared,
[Cowper, "The Castaway"]
inward (adj.)
Old English inweard "inmost; sincere; internal, intrinsic; deep," from Proto-Germanic *inwarth "inward" (source also of Old Norse innanverðr, Old High German inwart, Middle Dutch inwaert), from root of Old English inne "in" (see in (adv.)) + -weard (see -ward). As an adverb, Old English inneweard. As a noun in late Old English, "entrails, intestines."
ion (n.)
1834, introduced by English physicist and chemist Michael Faraday (suggested by the Rev. William Whewell, English polymath), coined from Greek ion, neuter present participle of ienai "go," from PIE root *ei- "to go." So called because ions move toward the electrode of opposite charge.
iopterous (adj.)

"having violet wings," 1855, from Greek ion "violet, violet color" (see iodine) + pteron "wing" (from PIE root *pet- "to rush, to fly").

ire (n.)
c. 1300, from Old French ire "anger, wrath, violence" (11c.), from Latin ira "anger, wrath, rage, passion," from PIE root *eis- (1), forming various words denoting passion (source also of Greek hieros "filled with the divine, holy," oistros "gadfly," originally "thing causing madness;" Sanskrit esati "drives on," yasati "boils;" Avestan aesma "anger;" Lithuanian aistra "violent passion"). Old English irre in a similar sense is unrelated; it from an adjective irre "wandering, straying, angry," which is cognate with Old Saxon irri "angry," Old High German irri "wandering, deranged," also "angry;" Gothic airzeis "astray," and Latin errare "wander, go astray, angry" (see err (v.)).
irrefragable (adj.)
"that cannot be refuted," literally "incapable of being broken down," 1530s, from French irréfragable (16c.) and directly from Late Latin irrefragabilis, from assimilated form of in- "not, opposite of" (see in- (1)) + Latin refragari "to oppose, contest," from re- "back" (see re-) + frag-, base of frangere "to break" (from PIE root *bhreg- "to break"). Related: irrefragably; irrefragability.
irrefrangible (adj.)
1722, "that cannot be broken or violated," from assimilated form of in- "not, opposite of" (see in- (1)) + refrangible. Related: Irrefrangibly.
irreverence (n.)
mid-14c., from Old French irreverence (13c.) or directly from Latin irreverentia "want of reverence, disrespect," from irreverentem (nominative irreverens) "disrespectful, irreverent," from assimilated form of in- "not, opposite of" (see in- (1)) + reverens, present participle of revereri "to stand in awe of" (see revere).
is (v.)
third person singular present indicative of be, Old English is, from Germanic stem *es- (source also of Old High German, German, Gothic ist, Old Norse es, er), from PIE *es-ti- (source also of Sanskrit asti, Greek esti, Latin est, Lithuanian esti, Old Church Slavonic jesti), third person singular form of root *es- "to be." Old English lost the final -t-. Until 1500s, pronounced to rhyme with kiss. Dialectal use for all persons (I is) is in Chaucer. Phrase it is what it is, indicating resigned acceptance of an unpleasant but inevitable situation or circumstance about which nothing truly positive can be said, is attested by 2001.
Isidore
masc. proper name, from French, from Latin Isidorus, from Greek Isidoros, literally "gift of Isis," from Isis (see Isis) + doron "gift" (from PIE root *do- "to give"). St. Isidore, archbishop of Seville (600-636) wrote important historical, etymological, and ecclesiastical works and in 2001 was named patron saint of computers, computer users, and the internet. Related: Isidorian.
island (n.)
1590s, earlier yland (c. 1300), from Old English igland, iegland "an island," from ieg "island" (from Proto-Germanic *aujo "thing on the water," from PIE root *akwa- "water") + land (n.). As an adjective from 1620s. Spelling modified 16c. by association with similar but unrelated isle. Similar formation in Old Frisian eiland, Middle Dutch eyland, German Eiland, Danish öland, etc. In place names, Old English ieg is often used of "slightly raised dry ground offering settlement sites in areas surrounded by marsh or subject to flooding" [Cambridge Dictionary of English Place-Names]. Island universe "solar system" (1846) translates German Weltinsel (von Humboldt, 1845). An Old English cognate was ealand "river-land, watered place, meadow by a river." Related: Islander.
isobar (n.)

1864, coined from Greek isos "equal" (see iso-) + baros "weight" (from PIE root *gwere- (1) "heavy"). Line connecting places with the same barometric pressure at the same time. Related: Isobaric.

Isold
fem. proper name, French Isolt, Iseut, of Germanic origin, literally "ice-rule," from Proto-Germanic *is "ice" (see ice (n.)) + *waldan "to rule" (from PIE root *wal- "to be strong").
isopod (n.)
"animal with legs equal in size and position," 1835, from French isopode, from Latin isopoda (neuter plural), from Greek iso- "equal, identical" (see iso-) + pod-, stem of pous "foot" (from PIE root *ped- "foot").
isostasy (n.)
"equilibrium from equality of pressure," 1889 (C.E. Dutton), from iso- + Greek stasis "setting, weighing, standing" (see stasis). Greek isostasios meant "in equipoise with, equivalent to."
isostatic (adj.)
"in equilibrium from equality of pressure," 1889, from isostasy + -ic.
isotonic (adj.)
"having or indicating equal tones," 1776, from Greek isotonos "of level pitch; equally stretched," from iso- "equal, identical" (see iso-) + tonos "tone," from PIE root *ten- "to stretch."
issue (n.)
c. 1300, "an exit," from Old French issue "a way out, a going out, exit; final event," from fem. past participle of issir "to go out," from Latin exire "go out, go forth; become public; flow, gush, pour forth" (source also of Italian uscire, Catalan exir), from ex- "out" (see ex-) + ire "to go," from PIE root *ei- "to go." Meaning "discharge of blood or other fluid from the body" is from 1520s; sense of "offspring, children" is from late 14c. Meaning "outcome of an action, consequence, result" is attested from late 14c., probably from this sense in French. Meaning "action of sending into publication or circulation" is from 1833. Legal sense developed from the notion of "end or result of pleadings in a suit (by presentation of the point to be determined by trial)," hence "the controversy over facts in a trial" (early 14c., Anglo-French) and transferred sense "point of contention between two parties" (early 15c.) and the general sense "an important point to be decided" (1836). Hence also the verbal phrase take issue with (1797, earlier join issue, 1690s) "take up an affirmative or negative position in a dispute with another." To have issues "have unresolved conflicts" is by 1990.
issue (v.)
mid-14c., of water, etc., "to flow out;" of persons, "come or go (out of a place), sally forth," from issue (n.) or else from Old French issu, past participle of issir. Transitive sense of "to send out" is from mid-15c.; specific sense of "to send out authoritatively" is from c. 1600. Meaning "supply (someone with something)" is from 1925. Related: Issued; issuing.
ithyphallic (adj.)
1795, in reference to a type of meter used in ancient Greek poetry (earlier as a noun, "poem in ithyphallic meter," 1610s), from Latin ithyphallicus, from Greek ithyphallikos, from ithyphallos "phallus carried in the festivals," from ithys "straight, straight upward" + phallos "erect penis" (see phallus). Credited to Archilochus, the meter was that of the Bacchic hymns, which were sung in the rites during which such phalluses were carried. Thus, in Victorian times, the word also meant "grossly indecent" (1864) and sometimes was used in scholarly works in its literal sense of "with erect penis" (1837).
itinerant (adj.)
1560s (attested in Anglo-Latin from late 13c.), from Late Latin itinerantem (nominative itinerans), present participle of itinerare "to travel," from Latin iter (genitive itineris) "a journey," from ire "go" (from PIE root *ei- "to go"). Originally in reference to circuit courts. As a noun from 1640s. Related: Itinerancy. Middle English had itineral "having to do with travel" (late 15c.).
itinerary (n.)
mid-15c., "route of travel," from Late Latin itinerarium "account of a journey, description of a route of travel, road-book," noun use of neuter of itinerarius "of a journey," from Latin itineris "a journey," from ire "go" (from PIE root *ei- "to go"). By early 15c. it meant "record of a journey;" extended sense "sketch of a proposed route, list of places to be included in a journey" is from 1856.
Ivan
masc. proper name, from Russian, literally "John," from Greek Ioannes (see John). As the personification of Russia, or the typical name for a Russian man (originally a Russian soldier), attested from 1870 (Ivanovitch).
ixnay
"no, no more," pig Latin for nix (v.).