Online Etymology Dictionary

Irishwoman (n.): c. 1200, from Irish (adj.) + woman (n.).
iron-bound (adj.): late 14c., from iron (n.) + bound (adj.1). Figurative use from 1807.
irons (n.): "iron shackles or fetters," mid-14c., plural of iron (n.).
ironstone (n.): 1520s, from iron (n.) + stone (n.). As a type of hard, white pottery, 1825.
irradiant (adj.): 1520s, from Latin irradiantem (nominative irradians), present participle of irradiare "to shine forth" (see irradiate). Related: Irradiantly.
irreclaimable (adj.): 1660s, from assimilated form of in- (1) "not, opposite of" + reclaimable (see reclaim (v.)). Related: Irreclaimably; irreclaimability.
irrecognition (n.): 1820, from assimilated form of in- (1) "not, opposite of" + recognition.
irreconciliation (n.): 1640s, from ir- "not, opposite of" + reconciliation. Irreconcilement in the same sense is from 1737.
irrumation (n.): "a putting of the erect penis in the mouth of another," 1866, from past participle stem of Latin irrumare, literally "to give to suck" (originally of the breast), from in- "in" + ruma "teat, female breast." Related: Irrumate (v.); irrumator.
irreption (n.): "a creeping in," 1590s, from Late Latin irreptionem (nominative irreptio), noun of action from past participle stem of Latin irrepere, from assimilated form of in- "in" (see in- (2)) + repere "to creep" (see reptile).
irresistance (n.): 1640s, from assimilated form of in- "not, opposite of" (see in- (1)) + resistance.
irresponsive (adj.): "not responsive, not answering," 1797, from assimilated form of in- "not, opposite of" + responsive.
irretractable (adj.): 1744, from assimilated form of in- "not, opposite of" + retractable.
irritating (adj.): "that causes annoyance," 1707, present participle adjective from irritate (v.). Related: Irritatingly. Earlier adjective forms were irritative (1680s), irritatory (1650s).
irrisory (adj.): "given to sneering or laughing derisively at others," 1824, from Late Latin irrisorius "mocking," from irrisor "a mocker," from stem of Latin irridere "to laugh at, make fun of," from assimilated form of in- "in" (see in- (2)) + ridere "to laugh" (see risible). Related: irrision (1520s), from Latin irrisionem, noun of action from the verb.
Isegrim: name of the wolf in Reynard and other beast-fables, from isen "iron" (see iron (n.)) + grima "mask, hood, helmet" (see grimace (n.)). In German, Isegrimm, Isengrimm.
Isis: Egyptian goddess, from Greek Isis, from Egyptian Hes, female deity identified by the Greeks with Io. She is distinguished in visual representations by the solar disc and cow horns on her head.
Ismailite (n.): also Ismaelite, 1570s, in reference to a Shi'ite Muslim sect, from Arabic Isma'iliy, the name of the sect that after 765 C.E. followed the Imamship through descendants of Ismail (Arabic for Ishmael), deceased eldest son of Jafar, the sixth Imam, rather than his surviving younger son.
islander (n.): "native or inhabitant of an island," 1540s, from island (n.) + -er (1).
isness (n.): "essence," 1865, in a translation of Hegel, from is + -ness.
isogloss (n.): 1925, from German Isogloss (1892); see iso- + gloss (n.2).
isochromatic (adj.): "having the same color," 1817, from iso- "equal, the same" + stem of chroma + -ic.
isodynamic (adj.): "having equal power or force," 1827, from iso- "the same, equal" + dynamic (adj.).
isogenous (adj.): "having the same or similar origin," 1856; see iso- "the same, equal" + -genous.
isolable (adj.): 1832, from isolate (v.) + -able on model of violate/violable, etc. Isolatable is recorded from 1870.
isomeric (adj.): "pertaining to or characterized by isomerism," 1831, from German isomerisch (Berzelius, 1831, in a paper on the "Composition of the Tartaric and Paratartaric Racemic Acids"), from Greek isomeres "sharing equality, having equal parts or shares," from iso- "equal" (see iso-) + meros "part, share" (see merit (n.)). Isomerous is from 1845 in botany, 1840 in chemistry.
isomorph (n.): "that which has the same form as another but belongs to a different group," 1850 of mineral substances; 1885 in zoology, probably a back-formation from isomorphism (q.v.), but used earlier in German (1821)..
isostatic (adj.): "in equilibrium from equality of pressure," 1889, from isostasy + -ic.
isonomia (n.): "equality before the law," c. 1600, from Italian or Latin, ultimately from Greek isonomia "equality of rights, the equality of a Greek democracy," from isos "equal, identical" (see iso-) + nomos "law" (see numismatics). Related: Isonomic (1851), which appears to be a separate formation in geology. Greek also had isoteleia in reference to an equality before the law sometimes granted to aliens in Athens, "equality of tax and tribute."
isopolity (n.): "equality of citizenship rights between different states," 1827, in reference to ancient Rome, from iso- "equal, identical" + polity.
issuable (adj.): 1560s, from issue (v.) + -able. Related: Issuably.
Istria: peninsula near the head of the Adriatic Sea, Latin Istria, from Istaevones, name of a Germanic people there, of unknown origin. Related: Istrian (c. 1600).
Italianism (n.): 1590s, from Italian + -ism.
Italic (adj.): "of or pertaining to ancient Italy," 1680s, from Latin Italicus, from Italia (see Italy). A word of historians and antiquarians. Earlier in the sense "pertaining to the Greek colonies in southern Italy" (1660s) and as the name of one of the orders of classical architecture (1560s).
Italiot (adj.): also Italiote, of or belonging to the ancient Greek settlements in southern Italy," 1650s, from Greek Italiotes, from Italia (see Italy).
Ithuriel's spear: the image is from "Paradise Lost," and turns up in late 19c. literature. The weapon caused anything it touched to assume its true form. Ithuriel is an archangel in the poem. The name is older and appears to be Kabbalistic.
ivied (adj.): 1771, from ivy (n.).
Islamophobia (n.): "hostility or discrimination against Muslims," supposedly rooted in dread or hatred of Islam, by 1996, from Islam + -phobia, as used in Jodeaophobia, Francophobia, etc.
The term [a report by the liberal think-tank Runnymede Trust] uses, 'Islamophobia,' is so recently coined that it has yet to be recognised in the Oxford English Dictionary, but according to the trust the phenomenon it refers to 'has existed in western countries and cultures for centuries.' ["Islamophobia," Third Way, April 1997]
Related: Islamophobic; Islamophobe.
Izod: clothing manufacturer trendy in the 1970s and 1980s, the company name was bought in 1930s from A.J. Izod, a London tailoring establishment. The surname (also Izzard, etc.) goes back to the Middle Ages and might be related to the proper name Isolt.
intraspecific (adj.): 1905, from intra- + specific, here representing species (n.).
ill-favored (adj.): of persons, "ugly," 1520s, from ill (adv.) + favored (q.v.).
ill-mannered (adj.): early 15c., from ill (adv.) + mannered.
ill-timed (adj.): 1690s, from ill (adv.) + time (v.).
ill-gotten (adj.): 1550s, from ill (adv.) + gotten.
illume (v.): "illuminate," c. 1600, from French illumer, contraction of illuminer, from Latin illuminare "light up, make light, illuminate" (see illumination). Related: Illumined; illumining.
illustrated (adj.): "provided with drawings, etc., as illustration," 1831, past participle adjective from illustrate (v.).
immobilise (adj.): chiefly British English spelling of immobilize (q.v.); for suffix, see -ize. Related: immobilisation; immobilised; immobilising.
immortalise (v.): chiefly British English spelling of immortalize (q.v.); for suffix, see -ize. Related: immortalisation; immortalised; immortalising.
immensurable (adj.): "immeasurable," c. 1500, from Old French immensurable, from Late Latin immensurabilis, from mensurabilis "able to be measured" (see mensurable).
immediatism (n.): "advocacy of immediate action" (originally with reference to abolition of slavery in the U.S.), 1834, from immediate + -ism.