Online Etymology Dictionary

internationalize (v.): 1864, from international (adj.) + -ize. Related: Internationalized; internationalizing.
intern (v.2): "to act or serve as as a (medical) intern," 1933, from intern (n.). Related: Interned; interning.
internality (n.): 1802, from internal + -ity.
innovatory (adj.): 1802; see innovate (v.) + -ory.
interchangeability (n.): 1763; see interchangeable + -ity.
interspace (n.): "space between" (any two things), early 15c., from Late Latin interspatium, from inter "between" (see inter-) + spatium (see space (n.)). As a verb, "fill or occupy the space between," 1832. Related: Interspaced; interspacing.
intertribal (adj.): also inter-tribal, 1850; see inter- "between" + tribe (n.) + -al (1).
interterritorial (adj.): also inter-territorial, 1827, from inter- "between" + territory + -al (1).
interturb (v.): "to disturb by interruption" (obsolete), 1550s, from Latin inturbus, past participle of inturbare "disturb by interruption," from in- "in" (see in- (2)) + turbare "to disturb, confuse" (see turbid). Related: Interturber (1530s).
intervenient (adj.): c. 1600, from Latin intervenientem (nominative interveniens), present participle of intervenire "to come between, interrupt," from inter- "between" (see inter-) + venire "come" (see venue). Related: Interveniently.
intervocalic (adj.): "between vowels," 1881, from inter- "between" + Latin vocalis "a vowel" (see vowel) + -ic.
interwoven (adj.): 1640s, past participle of interweave (q.v.).
ice age (n.): 1855, from ice (n.) + age (n.). Perhaps translating German Eiszeit (1837). An earlier term in the same sense was glacial epoch (1841). Local scientific men had noticed from the late 18c. evidence that the Alpine glaciers once had been much larger; in the 1830s stray boulders, moraines, and polished bedrock in northern Europe (formerly interpreted as relics of catastrophic floods) began to be understood as revealing the former presence of a large ice cap there. When Agassiz, a convert to the theory, came to America in 1846 he found similar evidence in New England. The glacial theory and the notion that there had been several worldwide ice ages seems to have been generally accepted by the 1870s.
intire (adj.): obsolete form of entire. Related: Intirely.
intonate (v.2): "to thunder, rumble," 1620s, from past participle stem of Latin intonare "to thunder, thunder forth," from in- (see in (2)) + tonare "to thunder" (see thunder (n.)). Related: Intonated; intonating.
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.
in totidem verbis: Latin phrase, "in just so many words," that is, "in these very words," from demonstrative of Latin totus "whole, entire" (see total (adj.)) + ablative plural of verbum "word" (see verb).
intranslatable (adj.): 1680s, from in- (1) "not, opposite of" + translate + -able. Related: Itranslatably; intranslatability.
intra-uterine (adj.): also intrauterine, 1820; see intra- "within" + uterine.
intra-orbital (adj.): also intraorbital, 1836, from intra- "within" + orbit (n.) + -al (1).
intranslatable (adj.): 1680s, from in- (1) "not, opposite of" + translate + -able. Related: Itranslatably; intranslatability.
intransmutable (adj.): 1690s, from in- (1) "not, opposite of" + transmute (v.) + -able). Related: Intransmutably; intransmutability.
intransmissible (adj.): 1650s, from in- (1) "not, opposite of" + transmissible. Related: Intransmissibly; intransmissibility.
intrench (v.): obsolete form of entrench (q.v.). Related: Intrenched; intrenchment.
intramercurial (adj.): "being within the orbit of the planet Mercury," 1859, especially in reference to a supposed planet orbiting there (sought in vain in the eclipse of 1860), from intra- "within, inside" + Mercury (Latin Mercurius) + -al (1). The idea originated in France in the 1840s with Urbain Le Verrier, who later became director of the Paris Observatory. There was some excitement about it in 1859 when a French doctor named Lescarbault claimed to have tracked it crossing the Sun's disk and convinced Le Verrier. It was sought in vain in the solar eclipses of 1860, '68, and '69. See Vulcan.
intrans.: abbreviation of intransitive (adj.).
intrigant (n.): also intriguant, "man given to intrigue," 1781, from French intrigant "male intriguer," from Italian intrigante, noun use of present participle of intrigare "to plot, meddle" (see intrigue (v.)).
intriguing (adj.): 1680s, "plotting, scheming," present-participle adjective from intrigue (v.). Meaning "exciting curiosity" is from 1909. Related: Intriguingly.
introducer (n.): 1620s, agent noun from introduce (v.).
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" (see versus).
intra-genic (adj.): also intragenic, "occurring within a gene," 1937, from intra- "within" + gene + -ic.
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).
intrust (v.): obsolete form of entrust (q.v.). Related: Intrusted; intrusting.
inturned (adj.): "turned inward," 1843, from in (adv.) + past participle of turn (v.).
inurbane (adj.): c. 1600, from Latin inurbanus "not civil or polite," from in- "not" (see in- (1) + urbanus "refined, courteous," literally "of a city" (see urban (adj.)). Related: Inurbanity.
inventory (v.): "make a list or catalogue of," c. 1600, from inventory (n.). Related: Inventoried; inventorying.
inveracity (n.): 1789, from in- (1) "not, opposite of" + veracity.
Inverness: literally "mouth of the (River) Ness (for which see Nessie), 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" (see infer).
invigilation (n.): "the act of watching," 1871, noun of action from invigilate (v.). Perhaps from German, where it is used earlier than in English.
invitatory (adj.): 1640s, from Latin invitatorius "inviting," from invitat-, past participle stem of invitare "to invite, treat, entertain" (see invitation).
invitational (adj.): 1894, from invitation + -al (1). The noun is by 1940, short for invitational tournament.
inwork (v.): 1680s, from in (adv.) + work (v.).
iodic (adj.): 1815, from French iodic (1812); see iodine + -ic.
iopterous (adj.): "having violet wings," 1855, from Greek ion "violet, violet color" (see iodine) + pteron "wing" (see ptero-).
iracund (adj.): "angry, inclined to wrath," 1707, from Late Latin iracundus, from ira "anger, wrath, rage, passion" (see ire (n.)). Related: Iracundulous (1765).
[T]he Severn is so mischievous and cholerick a river, and so often ruins the country with sudden inundations, since it rises in Wales, and consequently participates sometimes of the nature of that hasty, iracund people among whom 'tis born. [Thomas Browne, "Letters from the Dead to the Living," 1707]
Irian: Indonesian name for New Guinea, said to mean literally "cloud-covered."
ireful (adj.): c. 1300, from ire (n.) + -ful. Related: Irefully.
Irish (adj.): c. 1200, Irisce, "of Irish nationality;" see Irish (n.). Irish stew is attested from 1814; Irish lace is from 1851; Irish coffee is from 1950. Meaning "Irish in nature or character," it is attested from 1580s, and until 19c. often meaning "contradictory." In later use often mocking or dismissive, such as Irish apricot "potato," Irish daisy "common dandelion."
Irishism (n.): 1734, from Irish (adj.) + -ism.
Irishry (n.): "people of Ireland, the Irish people conceived as a company or body," late 14c., from Irish + -ry.