iodine (n.) Look up iodine at Dictionary.com
1814, formed by English chemist Sir Humphrey Davy (1778-1829) from French iode "iodine," coined 1812 by French chemist Joseph Louis Gay-Lussac from Greek ioeides "violet-colored," from ion "the violet; dark blue flower," + eidos "appearance" (see -oid). Davy added the chemical suffix -ine (2) to make it analogous with chlorine and fluorine. So called from the color of the vapor given off when the crystals are heated.
iodize (v.) Look up iodize at Dictionary.com
1841, from comb. form of iodine + -ize. Related: Iodized; iodizing.
ion (n.) Look up ion at Dictionary.com
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- (1) "to go, to walk" (cognates: Greek eimi "I go;" Latin ire "to go," iter "a way;" Old Irish ethaim "I go;" Irish bothar "a road" (from *bou-itro- "cows' way"), Gaulish eimu "we go," Gothic iddja "went," Sanskrit e'ti "goes," imas "we go," ayanam "a going, way;" Avestan ae'iti "goes;" Old Persian aitiy "goes;" Lithuanian eiti "to go;" Old Church Slavonic iti "go;" Bulgarian ida "I go;" Russian idti "to go"). So called because ions move toward the electrode of opposite charge.
Ionian (adj.) Look up Ionian at Dictionary.com
"of Ionia," the districts of ancient Greece inhabited by the Ionians (including Attica and the north coast of the Peloponnesus, but especially the coastal strip of Asia Minor, including the islands of Samos and Chios). The name (which Herodotus credits to an ancestral Ion, son of Apollo and Creusa) probably is pre-Greek, perhaps related to Sanskrit yoni "womb, vulva," and a reference to goddess-worshipping people.

Also used of the sea that lies between Italy and the northern Peloponnesus (1630s). The musical Ionian mode (1844) corresponds to our basic major scale but was characterized by the Greeks as soft and effeminate, as were the Ionians generally.
The Ionians delighted in wanton dances and songs more than the rest of the Greeks ... and wanton gestures were proverbially termed Ionic motions. [Thomas Robinson, "Archæologica Græca," 1807]
Ionic (adj.) Look up Ionic at Dictionary.com
"pertaining to Ionia," 1570s of music; 1580s of architecture, from Latin Ionicus, from Greek Ionikos (see Ionian).
ionic (adj.) Look up ionic at Dictionary.com
"pertaining to ions," 1890, from ion + -ic.
ionization (n.) Look up ionization at Dictionary.com
1891; see ionize + -ation.
ionize (v.) Look up ionize at Dictionary.com
1896, from ion + -ize. Related: Ionized; ionizing.
ionosphere (n.) Look up ionosphere at Dictionary.com
1926, from ion + sphere. Coined by Scottish radar pioneer Robert A. Watson-Watt (1892-1973). So called because it contains many ions.
iota (n.) Look up iota at Dictionary.com
"very small amount," 1630s, figurative use of iota, ninth and smallest letter in the Greek alphabet. Modern use is after Matt. v:18 (see jot), but iota in classical Greek also was proverbially used of anything very small. The letter name is from Semitic (compare Hebrew yodh).
Iowa Look up Iowa at Dictionary.com
organized as a U.S. territory 1838; admitted as a state 1846, ultimately from the name of the native people, of the Chiwere branch of the Aiouan family; said to be from Dakota ayuxba "sleepy ones."
ipecac Look up ipecac at Dictionary.com
1710, borrowing via Portuguese of a shortened form of Tupi ipecacuana (a word attested in English from 1682), a medicinal plant of Brazil. The Indian word is said to mean "small plant causing vomit."
ipse dixit Look up ipse dixit at Dictionary.com
Latin, literally "he (the master) said it," translation of Greek autos epha, phrase used by disciples of Pythagoras when quoting their master.
ipseity (n.) Look up ipseity at Dictionary.com
1650s, from Latin ipse "self" + -ity.
ipsilateral (adj.) Look up ipsilateral at Dictionary.com
1907, from Latin ipse "self" + lateral.
ipso facto Look up ipso facto at Dictionary.com
Latin, literally "by that very fact."
ir- Look up ir- at Dictionary.com
assimilated form of Latin prefixes in- (see in-) before -r-.
Ira Look up Ira at Dictionary.com
masc. proper name, from Hebrew, literally "watchful," from stem of 'ur "to awake, to rouse oneself."
Iran Look up Iran at Dictionary.com
from Persian Iran, from Middle Persian Ērān "(land) of the Iranians," genitive plural of ēr- "an Iranian," from Old Iranian *arya- (Old Persian ariya-, Avestan airya-) "Iranian", from Indo-Iranian *arya- or *ārya- (see Aryan), a self-designation, perhaps meaning "compatriot." In 1935 the government of Reza Shah Pahlavi requested governments with which it had diplomatic relations to call his country Iran, after the indigenous name, rather than the Greek-derived Persia.
Iranian Look up Iranian at Dictionary.com
1841 (adj.); 1873 (n.), from Iran + -ian.
Iraq Look up Iraq at Dictionary.com
country name, 1920, from an Arabic name attested since 6c. for the region known in Greek as Mesopotamia; often said to be from Arabic `araqa, covering notions such as "perspiring, deeply rooted, well-watered," which may reflect the impression the lush river-land made on desert Arabs. But the name may be from, or influenced by, Sumerian Uruk (Biblical Erech), anciently a prominent city in what is now southern Iraq (from Sumerian uru "city").
irascibility (n.) Look up irascibility at Dictionary.com
1750, from irascible + -ity.
irascible (adj.) Look up irascible at Dictionary.com
late 14c., from Middle French irascible (12c.) and directly from Late Latin irascibilis, from Latin irasci "be angry, be in a rage," from ira "anger" (see ire).
irate (adj.) Look up irate at Dictionary.com
1838, from Latin iratus "angry, enraged, violent, furious," past participle of irasci "grow angry," from ira "anger" (see ire).
ire (n.) Look up ire at Dictionary.com
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" cognates: 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 from an adjective irre "wandering, straying, angry," 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.)). (cognates: Avestan aešma- "anger," Lithuanian aistra "violent passion," Latin ira "anger")
Ireland Look up Ireland at Dictionary.com
12c., Anglo-Norman, with land + native Eriu (see Irish).
Irene Look up Irene at Dictionary.com
fem. proper name, from French Irène, from Latin Irene, from Greek Eirene, literally "peace, time of peace."
irenic (adj.) Look up irenic at Dictionary.com
1864; see eirenic.
irenology (n.) Look up irenology at Dictionary.com
"study of peace," 1974, from Greek eirene "peace" + -ology. Related: Irenological.
Irgun Look up Irgun at Dictionary.com
militant Zionist organization, 1946, from Modern Hebrew, literally "organization," in full Irgun Zvai Leumi "national military organization."
iridescence (n.) Look up iridescence at Dictionary.com
1804, from iridescent + -ence. Related: Iridescency (1799).
iridescent (adj.) Look up iridescent at Dictionary.com
1796, literally "rainbow-colored," coined from comb. form of Latin iris (genitive iridis) "rainbow" (see iris). Related: Iridescently.
iridium (n.) Look up iridium at Dictionary.com
1804, Modern Latin, coined by its discoverer, English chemist Smithson Tennant (1761-1815) from Greek iris (genitive iridos) "rainbow;" so called for "the striking variety of colours which it gives while dissolving in marine acid" [Tennant]
iris (n.) Look up iris at Dictionary.com
late 14c., flowering plant (Iris germanica), also "prismatic rock crystal," from Latin iris (plural irides) "iris of the eye, iris plant, rainbow," from Greek iris (genitive iridos) "a rainbow; the lily; iris of the eye," originally "messenger of the gods," personified as the rainbow. The eye region was so called (early 15c. in English) for being the colored part; the Greek word was used of any brightly colored circle, "as that round the eyes of a peacock's tail" [Liddell & Scott].
Irish (n.) Look up Irish at Dictionary.com
c.1200, Irisce, from stem of Old English Iras "inhabitant of Ireland," from Old Norse irar, ultimately from Old Irish Eriu (accusative Eirinn, Erinn) "Erin," which is from Old Celtic *Iveriu (accusative *Iverionem, ablative *Iverione), perhaps from PIE *pi-wer- "fertile," literally "fat," from root *peie- "to be fat, swell" (see fat (adj.)).

Meaning "temper, passion" is 1834, American English (first attested in writings of Davy Crockett), from the legendary pugnacity of Irish people. Irish-American is from 1832; Irish stew is attested from 1814; Irish coffee is from 1950. Wild Irish (late 14c.) originally were those not under English rule; Black Irish in reference to those of Mediterranean appearance is from 1888.
Irishman (n.) Look up Irishman at Dictionary.com
c.1200, from Irish + man (n.).
irk (v.) Look up irk at Dictionary.com
mid-15c., irken "be weary of, be disgusted with;" earlier intransitive, "to feel weary" (early 14c.). Of uncertain origin, perhaps related to Old Norse yrkja "work" (from PIE root *werg- "to work;" see organ), or Middle High German erken "to disgust." Modern sense of "annoy" is from late 15c. An adjective, irk "weary, tired" is attested from c.1300 in northern and midlands writing.
irksome (adj.) Look up irksome at Dictionary.com
"bothersome, burdensome," early 15c., from irk + -some (1). Related: Irksomely; irksomeness.
Irma Look up Irma at Dictionary.com
fem. proper name; see Emma.
iron (n.) Look up iron at Dictionary.com
Old English isærn (with Middle English rhotacism of -s-) "the metal iron; an iron weapon," from Proto-Germanic *isarnan (cognates: Old Saxon isarn, Old Norse isarn, Middle Dutch iser, Old High German isarn, German Eisen) "holy metal" or "strong metal" (in contrast to softer bronze) probably an early borrowing of Celtic *isarnon (compare Old Irish iarnhaiarn), from PIE *is-(e)ro- "powerful, holy," from PIE *eis "strong" (cognates: Sanskrit isirah "vigorous, strong," Greek ieros "strong").
Right so as whil that Iren is hoot men sholden smyte. [Chaucer, c.1386]
Chemical symbol Fe is from the Latin word for the metal, ferrum (see ferro-). Meaning "metal device used to press or smooth clothes" is from 1610s. The adjective is Old English iren, isern. To have (too) many irons in the fire "to be doing too much at once" is from 1540s. Iron lung "artificial respiration tank" is from 1932.
iron (v.) Look up iron at Dictionary.com
c.1400, irenen, "to make of iron," from iron (n.). Meaning "press clothes" (with a heated flat-iron) is recorded from 1670s. Related: Ironed; ironing.
Iron Age Look up Iron Age at Dictionary.com
1590s, originally from Greek and Roman mythology, the last and worst age of the world; the archaeological sense of "period in which humans used iron tools and weapons" is from 1879.
Iron Cross Look up Iron Cross at Dictionary.com
from German das eiserne kreuz, instituted by Frederick Wilhelm III of Prussia, originally for distinguished military service in the wars against Napoleon.
Iron Curtain (n.) Look up Iron Curtain at Dictionary.com
in reference to the Soviet occupation of Eastern Europe, famously coined by Winston Churchill March 5, 1946, in speech at Westminster College, Fulton, Missouri, but it had been used earlier in this context (for example by U.S. bureaucrat Allen W. Dulles at a meeting of the Council on Foreign Relations, Dec. 3, 1945). The figurative sense of "impenetrable barrier" is attested from 1819, and the specific sense of "barrier at the edge of the sphere of influence of the Soviet Union" is recorded from 1920. During World War II, Goebbels used it in German (ein eiserner Vorhang) in the same sense. Its popular use in the U.S. dates from Churchill's speech.
iron-gray Look up iron-gray at Dictionary.com
Old English isengrægum; see iron (n.) + gray. The color of freshly broken cast iron.
iron-on (adj.) Look up iron-on at Dictionary.com
1959, from the verbal phrase, from iron (v.) + on (adv.).
ironclad (adj.) Look up ironclad at Dictionary.com
1852, of warships, American English, from iron (n.) + clad. Of contracts, etc., 1884. As a noun meaning "iron-clad ship," it is attested from 1862.
ironic (adj.) Look up ironic at Dictionary.com
1620s, from Late Latin ironicus, from Greek eironikos "dissembling, putting on a feigned ignorance," from eironeia (see irony). Related: Ironical (1570s); ironically.
ironing (n.) Look up ironing at Dictionary.com
"act of pressing and smoothing clothes with a heated flat-iron," c.1710, from present participle of iron (v.). Ironing board attested from 1843.
Ironside Look up Ironside at Dictionary.com
name given to a man of great hardihood or bravery, c.1300, first applied to Edmund II, king of England (d.1016), later also to Oliver Cromwell and his troops. Old Ironsides as a nickname of U.S.S. "Constitution" dates from that ship's defeat of H.M.S. "Guerriere" on Aug. 19, 1812, in the War of 1812.