Online Etymology Dictionary

irreparable (adj.): early 15c., from Old French irréparable (12c.), from Latin irreparabilis "not to be repaired or recovered," from assimilated form of in- "not, opposite of" (see in- (1)) + reparabilis "that can be repaired" (see repair (v.)). Irrepairable, from the English verb, was used 16c.-17c. but seldom was seen after.
irresponsible (adj.): 1640s, "not legally answerable for conduct or actions," from assimilated form of in- (1) "not, opposite of" + responsible. Meaning "not acting with a sense of responsibility" is from 1680s. Related: Irresponsibly.
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).
irrevocable (adj.): also irrevokable, late 14c., from Latin irrevocabilis "that cannot be recalled, unalterable," from assimilated form of in- "not, opposite of" (see in- (1)) + revocabilis (see revoke). Related: Irrevocably.
irrigate (v.): "supply land with water," 1610s, from Latin irrigatus, past participle of irrigare "lead water to, refresh, irrigate, flood," from assimilated form of in- "into, in, on, upon" (see in- (2)) + rigare "to water, to moisten," of uncertain origin. Perhaps [Watkins] from PIE *reg- (2) "moist" (see rain (n.)). De Vaan offers as possibilities the root of regere "to direct, lead," on the notion of leading water onto the fields, or to the root of rigere "be stiff," literally "stretch." The first better suits the sense, but has phonetic problems.

Related: Irrigated; irrigating. In Middle English it was an adjective, "watered, flooded" (mid-15c.). Other adjectival forms have been irriguous (1650s), irrigative (1842), irrigatorial (1867).
irritate (v.): 1530s, "stimulate to action, rouse, incite," from Latin irritatus, past participle of irritare "excite, provoke, annoy;" according to de Vaan, probably a verb from Proto-Italic *rito- "stirred," from the same PIE root that produced English run (v.). Meaning "annoy, make impatient" in English is from 1590s. The earlier verb in English was irrite (mid-15c.), from Old French irriter. Related: Irritated; irritating.
Irwin: masc. proper name, Old English Eoforwine "boar-friend;" often confused with Irving, Irvin, which are from Irvine, Ayrshire, or Irving, Dumfries.
Isaac: masc. proper name, name of a biblical patriarch, from Late Latin, from Greek Isaak, from Hebrew Yitzhaq, literally "he laughs," imperf. of tzahaq "he laughed."
Isabel: fem. proper name, a form of Elizabeth that seems to have developed in Provence. A popular English name in the Middle Ages; pet forms included Ibb, Libbe, Nibb, Tibb, Bibby, and Ellice. The Spanish form was Isabella, which is attested as a color name ("greyish-yellow") in English from c. 1600; the Isabella who gave her name to it has not been identified, and the usual stories are too late for the date. Related: Isabelline (adj.).
Isaiah: masc. proper name, name of a biblical prophet and of the book credited to him, from Hebrew Yesha'yah, abbreviated form of Yesha'yahu, literally "salvation of the Lord," from yesha, yeshua "salvation, deliverance." Related: Isaian
Iscariot: surname of Judas, betrayer of Jesus, in New Testament, from Latin Iscariota, from Greek Iskariotes, said to be from Hebrew ishq'riyoth "man of Kerioth" (a place in Palestine). In English from 1640s as a noun meaning "traitor." Related: Iscariotical.
ischium (n.): "the seat bone," 1640s, from Latin, from Greek iskhion "hip joint," in plural, "the hips," probably from iskhi "loin," a word of unknown origin. Related: Ischiatic.
Ishihara: popular type of colorblindness test, 1924, from Japanese ophthalmologist Shinobu Ishihara (1879-1963), who devised it in 1917.
Ishmael: masc. proper name, biblical son of Abraham and Hagar, driven into the wilderness with his mother, from Hebrew Yishma'el, literally "God hears," from yishma, imperf. of shama "he heard." The Arabs claim descent from him. Figurative sense of "an outcast," "whose hand is against every man, and every man's hand against him" is from Gen. xvi:12. Related: Ishmaelite.
Ishtar: ancient Sumero-Babylonian goddess of love and fertility, counterpart of Phoenician Astarte (q.v.), from Akkadian Ishtar.
Isidore: masc. proper name, from French, from Latin Isidorus, from Greek Isidoros, literally "gift of Isis," from Isis (see Isis) + doron "gift" (see date (n.1)). 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.
isinglass (n.): purest commercial form of gelatin, 1520s, apparently a perversion of Dutch huysenblas, literally "sturgeon bladder," from huysen "sturgeon" + blas "bladder," from PRoto-Germanic *bles-, extended form of root *bhle- (2) "to blow, swell" (see bole). So called because the substance was obtained from the air-bladders of certain freshwater fishes.
Islam (n.): "religious system revealed by Muhammad," 1816, from Arabic islam, literally "submission" (to the will of God), from root of aslama "he resigned, he surrendered, he submitted," causative conjunction of salima "he was safe," and related to salam "peace."
... Islam is the only major religion, along with Buddhism (if we consider the name of the religion to come from Budd, the Divine Intellect, and not the Buddha), whose name is not related to a person or ethnic group, but to the central idea of the religion. ["The Heart of Islam: Enduring Values for Humanity," Seyyed Hossein Nasr, 2002]
Earlier English names for the faith include Mahometry (late 15c.), Muhammadism (1610s), Islamism (1747), and Ismaelism (c. 1600; see Ismailite). The Ismailites were not numerous in Islam, but among them were the powerful Fatimid dynasty in Egypt and the Assassins, both of which loomed large in European imagination. This use also is in part from Ishmaelite, a name formerly given (especially by Jews) to Arabs, as descendants of Ishmael (q.v.).
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 *akwa- "water;" see aqua-) + land (n.). As an adjective from 1620s.

Spelling modified 15c.-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.
isle (n.): late 13c., ile, from Old French ile, earlier isle, from Latin insula "island," a word of uncertain origin.

Perhaps (as the Ancients guessed) from in salo "(that which is) in the (salty) sea," from ablative of salum "the open sea," related to sal "salt" (see salt (n.)). De Vaan finds this "theoretically possible as far as the phonetics go, but being 'in the sea' is not a very precise description of what an island is; furthermore, the Indo-Europeans seem to have indicated with 'island' mainly 'river islands.' ... Since no other etymology is obvious, it may well be a loanword from an unknown language." He proposes the same lost word as the source of Old Irish inis, Welsh ynys "island" and Greek nesos "island." The -s- was restored first in French, then in English in the late 1500s.
-ism: word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.
isobar (n.): 1864, coined from Greek isos "equal" (see iso-) + baros "weight," from PIE root *gwere- (2) "heavy" (see grave (adj.)). Line connecting places with the same barometric pressure at the same time. Related: Isobaric.
isolate (v.): "to set or place apart, to detach so as to make alone," by 1786, a back-formation from isolated (q.v.).
The translation of this work is well performed, excepting that fault from which few translations are wholly exempt, and which is daily tending to corrupt our language, the adoption of French expressions. We have here evasion for escape, twice or more times repeated; brigands very frequently; we have the unnecessary and foolish word isolate; and, if we mistake not, paralize, which at least has crept in through a similar channel. Translators cannot be too careful on this point, as it is a temptation to which they are constantly exposed. ["The British Critic," April 1799]
As a noun, "something isolated," 1890; from earlier adjectival use (1819), which is from Italian isolato or Medieval Latin insulatus.
isometric (adj.): 1838, literally "of the same measure," from iso- "the same, equal" + -metric. The components are Greek: isos "equal, identical" + metron "a measure." Originally a method of using perspective in drawing; later in reference to crystals. The physiological sense relating to muscular action is from 1889, from German isometrisch in this sense (1882).
isosceles (adj.): "having two equal sides," 1550s, from Late Latin isosceles, from Greek isoskeles "with equal legs; isosceles; that can be divided into two equal parts," from isos "equal, identical" (see iso-) + skelos "leg," from PIE *skel-es-, from root *(s)kel- (3) "crooked" (see scoliosis).
isotope (n.): 1913, literally "having the same place," from Greek isos "equal" (see iso-) + topos "place" (see topos); so called because, despite having different atomic weights, the various forms of an element occupy the same place on the periodic table. Introduced by British chemist Frederick Soddy (1877-1956) on suggestion of his friend, the Scottish writer and doctor Margaret Todd Margaret Todd (c. 1859-1918). Related: Isotopic.
Israel: Old English Israel, "the Jewish people, the Hebrew nation," from Latin Israel, from Greek, from Hebrew yisra'el "he that striveth with God" (Gen. xxxii:28), symbolic proper name conferred on Jacob and extended to his descendants, from sara "he fought, contended" + El "God." As the name of an independent Jewish state in the Middle East, it is attested from 1948. Compare Israeli, Israelite.
Issachar: son of Jacob by Leah (Old Testament) and name of a biblical tribe of Israel, from Greek issakhar, from Hebrew Yissakhar, probably [Klein] from Hebrew yesh sakhar "there is a reward" (see Gen. xxx:18).
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- (1) "to go" (see ion).

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.
-ist: word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.

Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.
-istic: adjectival word-forming element, from French -istique or directly from Latin -isticus, from Greek -istikos, a compound of the adjectival suffix -ikos (see -ic) + the noun suffix -istes (see -ist).
isthmus (n.): 1550s, from Latin isthmus, from Greek isthmos "narrow passage, narrow neck of land between two seas," originally especially that of Corinth, a word of unknown origin. Perhaps from eimi "to go" + suffix -thmo (compare ithma "a step, movement").
it (pron.): Old English hit, neuter nominative and accusative of third person singular pronoun, from Proto-Germanic demonstrative base *khi- (source also of Old Frisian hit, Dutch het, Gothic hita "it"), from PIE *ko- "this" (see he). Used in place of any neuter noun, hence, as gender faded in Middle English, it took on the meaning "thing or animal spoken about before."

The h- was lost due to being in an unemphasized position, as in modern speech the h- in "give it to him," "ask her," is heard only "in the careful speech of the partially educated" [Weekley]. It "the sex act" is from 1610s; meaning "sex appeal (especially in a woman)" first attested 1904 in works of Rudyard Kipling, popularized 1927 as title of a book by Elinor Glyn, and by application of It Girl to silent-film star Clara Bow (1905-1965). In children's games, the meaning "the one who must tag or catch the others" is attested from 1842.

From Old English as nominative of an impersonal verb or statement when the thing for which it stands is implied (it rains, it pleases me). After an intransitive verb, used transitively for the action denoted, from 1540s (originally in fight it out). That's it "there is no more" is from 1966; this is it "the anticipated or dreaded moment has arrived" is from 1942.
Italian (n.): early 15c., "native of Italy," from Italian Italiano, from Italia "Italy" (see Italy). Meaning "the Italian language" is late 14c. As an adjective from 1510s. Earlier the Italians were the Italies (late 14c.).
italic (adj.): "type of printing with lines sloping to the right," 1610s, from Latin italicus "Italian, of Italy," from Italia (see Italy). So called because it was introduced in 1501 by Aldus Manutius, printer of Venice (who also gave his name to Aldine), and first used in his edition of Virgil, which was dedicated to Italy. As a noun, "italic type," 1670s.
[Italics] pull up the reader and tell him not to read heedlessly on, or he will miss some peculiarity in the italicized word. [Fowler]
Earlier (1570s) the word was used in English for the plain, sloping style of handwriting (opposed to gothic), and italic printing sometimes in English was called cursive (and also Aldine). Often, but not always, for emphasis; in manuscripts indicated by an underscored line. Related: Italics.
The Italic words in the Old and New Testament are those, which have no corresponding words in the original Hebrew or Greek; but are added by the translators, to complete or explain the sense. [Joseph Robertson, "An Essay on Punctuation," 1785]
itch (n.): "irritating tingling sensation in the skin," also "skin inflammation caused by a burrowing mite," Old English gicce, from giccan (v.) "to itch" (see itch (v.)). Sense of "restless desire" is first attested 1530s; itching in this sense is from mid-14c.
item (n.): late 14c., originally an adverb, "moreover, in addition," from Latin item (adv.) "likewise, just so, moreover," probably from ita "thus," id "it" (see id) + adverbial ending -tem (compare idem "the same").

The Latin adverb was used to introduce a new fact or statement, and in French and English it was used before every article in an enumeration (such as an inventory or bill). This practice led to the noun sense "an article of any kind" (1570s). Meaning "detail of information" (especially in a newspaper) is from 1819; item "sexually linked unmarried couple" is 1970, probably from notion of being an item in the gossip columns.
iterate (v.): 1530s, "to do again, repeat," back-formation from iteration, or else from Latin iteratus, past participle of iterare "do again, repeat." Related: Iterated; iterating.
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" (see ion). Originally in reference to circuit courts. As a noun from 1640s. Related: Itinerancy. Middle English had itineral "having to do with travel" (late 15c.).
-itis: word-forming element in medicine denoting "diseases characterized by inflammation" (of the specified part), Modern Latin, from Greek -itis, feminine of adjectival suffix -ites "pertaining to." Feminine because it was used with an implied nosos "disease," a feminine noun; especially in arthritis (nosos) "(disease) of the joints." Arthritis (16c.) was one of the earliest appearances of the suffix in English and from it the suffix was abstracted in other uses.
its (pron.): neuter possessive pronoun; late 16c., from it + genitive/possessive ending 's (q.v.). "[A]t first commonly written it's, a spelling retained by some to the beginning of the 19c." [OED]. The apostrophe came to be omitted, perhaps because it's already was established as a contraction of it is, or by general habit of omitting apostrophes in personal pronouns (hers, yours, theirs, etc.).

The neuter genitive pronoun in Middle English was his, but the clash between grammatical gender and sexual gender, or else the application of the word to both human and non-human subjects, evidently made users uncomfortable. Restriction of his to the masculine and avoidance of it as a neuter pronoun is evidenced in Middle English, and of it and thereof (as in KJV) were used for the neuter possessive. In literary use, his as a neuter pronoun continued into the 17c. In Middle English, simple it sometimes was used as a neuter possessive pronoun (c. 1300).
itself (pron.): late 14c., from Old English hit sylf, from it + self. Since 17c. usually regarded as its self (thus its own self, etc.).
itsy-bitsy (adj.): "charmingly small," 1890, from itty (baby-talk form of little) and/or bitsy. Bitsy-itsy is recorded from 1875. Itty-bitty from 1855; tiddy-itty from 1852.
The fond old captain used to talk of her very much as if she were six months old, and fractions in teething, calling her his Peetums-keetums, his Pitsy-itsy-kitsy and such like, which annoyed the girl, .... ["M.B.," "John's Wife," in "Tales of the Day," 1861]
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).
ivory (n.): mid-13c. (late 12c. as a surname), Anglo-French ivorie, from Old North French ivurie (12c.), from Medieval Latin eborium "ivory," noun use of neuter of Latin eboreus "of ivory," from ebur (genitive eboris) "ivory," probably via Phoenician from an African source (compare Egyptian ab "elephant," Coptic ebu "ivory").

It replaced Old English elpendban, literally "elephant bone." Applied in slang to articles made from it, such as dice (1830) and piano keys (1818). As a color, especially in reference to human skin, it is attested from 1580s. Ivories as slang for "teeth" dates from 1782. Black ivory was ivory burnt and powdered, used as a pigment (1810); the sense "African slaves as an article of commerce" is attested from 1834.
Mr. Dunlap then asked the witness what he himself traded in, when on the African coast, and he replied "sometimes in black ivory;" but, being more closely pressed to explain what he meant by "black ivory," he admitted that when he could not get a cargo of real ivory, he took one of slaves. ["Trial of the Twelve Spanish Pirates," Boston, 1834]
Related: Ivoried; ivorine.
ivy (n.): climbing plant, Old English ifig, from West Germanic *ibakhs (source also of Middle Low German iflof, Dutch eiloof, Old High German ebahewi, German Efeu), a word of unknown origin; the second element in the Old High German word might be heu "hay."

Ivy bush as a sign of a tavern where wine is served is attested from mid-15c. (the ivy being sacred to Bacchus). Ivy League, inspired by the image of old, ivy-mantled walls, dates to 1935, originally in reference to a conference of football teams agreeing to organize teams and play games by set rules; it consists of Brown, Columbia, Cornell, Dartmouth, Harvard, Pennsylvania, Princeton, and Yale.
Incidentally, "Ivy League" is a poor name; it suggests that athletic morality is concentrated in a few very old colleges. Obviously, membership should be determined not by the amount of ivy on an institution's walls, but by its willingness to adopt and follow certain fundamental principles of education and sport. ["Princeton Alumni Weekly," Dec. 6, 1935]
ixnay: "no, no more," pig Latin for nix (v.).
izard (n.): chamois-like antelope of the Pyrenees, 1791, from French isard, Gascon isart, "perhaps of Iberian origin" (according to French sources), or [Klein] from Basque (which has izzara "star").
intestate (adj.): late 14c., from Old French intestat (13c.) and directly from Latin intestatus "having made no will," from in- "not" (see in- (1)) + testatus, past participle of testari "make a will, bear witness" (see testament). As a noun, "one who has not made out a will," from 1650s.