Online Etymology Dictionary

yean (v.): Old English eanian "to bring forth" (young), especially in reference to sheep or goats, from Proto-Germanic *agwnojanan (cf. Dutch oonen), perhaps from PIE *agwhnos "lamb" (cf. Greek amnos "lamb," Latin agnus, Old Church Slavonic agne, Old Irish van, Welsh oen). Yeanling "young lamb, kid" is recorded from 1630s.
year (n.): Old English gear (West Saxon), ger (Anglian) "year," from Proto-Germanic *jæram "year" (cf. Old Saxon, Old High German jar, Old Norse ar, Danish aar, Old Frisian ger, Dutch jaar, German Jahr, Gothic jer "year"), from PIE *yer-o-, from root *yer-/*yor- "year, season" (cf. Avestan yare (nominative singular) "year;" Greek hora "year, season, any part of a year," also "any part of a day, hour;" Old Church Slavonic jaru, Bohemian jaro "spring;" Latin hornus "of this year;" Old Persian dušiyaram "famine," literally "bad year"). Probably originally "that which makes [a complete cycle]," and from verbal root *ei- meaning "to do, make."
yearbook (n.): 1580s, "book of reports of cases in law-courts for that year," from year + book (n.). Meaning "book of events and statistics of the previous year" is recorded from 1710. Sense of "graduating class album" is attested from 1926, American English.
yearling (n.): mid-15c., from year + -ling.
yearly (adj.): Old English gearlic; see year + -ly (1).
yearn (v.): Old English geornan (Mercian), giernan (West Saxon), giorna (Northumbrian), from Proto-Germanic *gernijanan (cf. Gothic gairnjan "to desire," German begehren "to desire"), from *gernaz (cf. Old High German gern, Old Norse gjarn "desirous," Old English georn "eager, desirous," German gern "gladly, willingly"), from PIE root *gher- "to like, want" (see hortatory). Related: Yearned; yearning.
yeast (n.): Old English gist "yeast," common West Germanic (cf. Middle High German gest, German Gischt "foam, froth," Old High German jesan, German gären "to ferment"), from PIE *jes- "boil, foam, froth" (cf. Sanskrit yasyati "boils, seethes," Greek zein "to boil," Welsh ias "seething, foaming").
yeasty (adj.): 1590s, from yeast + -y (2).
yegg (n.): "thief, burglar," especially "safecracker," 1903, underworld slang, of unknown origin, said to be from John Yegg, a Swedish tramp, or from German Jäger "huntsman."
yell (v.): Old English gellan (Mercian), giellan (West Saxon), class III strong verb (past tense geal, past participle gollen), from Proto-Germanic *gelnanan (cf. Old Norse gjalla "to resound," Middle Dutch ghellen, Dutch gillen, Old High German gellan, German gellen "to yell"), extended form of root of Old English galan "to sing" (source of the -gale in nightingale); from PIE *ghel- "to cry out, shout, sing." Related: Yelled; yelling.
yell (n.): late 14c., originally in Scottish, from yell (v.).
yellow (adj.): Old English geolu, geolwe, from Proto-Germanic *gelwaz (cf. Old Saxon, Old High German gelo, Middle Dutch ghele, Dutch geel, Middle High German gel, German gelb, Old Norse gulr, Swedish gul "yellow"), from PIE *ghel- "yellow, green" (see Chloe).

Meaning "light-skinned" (of blacks) first recorded 1808. Applied to Asiatics since 1787, though the first recorded reference is to Turkish words for inhabitants of India. Yellow peril translates German die gelbe gefahr. Sense of "cowardly" is 1856, of unknown origin; the color was traditionally associated rather with treachery. Yellow-bellied "cowardly" is from 1924, probably a rhyming reduplication of yellow; earlier yellow-belly was a sailor's name for a half-caste (1867) and a Texas term for Mexican soldiers (1842, based on the color of their uniforms). Yellow dog "mongrel" is attested from c.1770; slang sense of "contemptible person" first recorded 1881. Yellow fever attested from 1748, American English (jaundice is a symptom).
yellow (v.): "to become yellow," Old English geoluwian, from the source of yellow (adj.). Related: Yellowed; yellowing.
yellow journalism: "sensational chauvinism in the media," 1898, American English, from newspaper agitation for war with Spain; originally "publicity stunt use of colored ink" (1895) in reference to the popular Yellow Kid" character (his clothes were yellow) in Richard Outcault's comic strip "Shantytown" in the "New York World."
yellow ribbon: The American folk custom of wearing or displaying a yellow ribbon to signify solidarity with loved ones or fellow citizens at war originated during the U.S. embassy hostage crisis in Iran in 1979. It does not have a connection to the American Civil War, beyond the use of the old British folk song "Round Her Neck She Wore A Yellow Ribbon" in the John Wayne movie of the same name, with a Civil War setting, released in 1949. The story of a ribbon tied to a tree as a signal to a convict returning home that his loved ones have forgiven him is attested from 1959, but the ribbon in that case was white.

The ribbon color seems to have changed to yellow first in a version retold by newspaper columnist Pete Hamill in 1971. The story was dramatized in June 1972 on ABC-TV (James Earl Jones played the ex-con). Later that year, Irwin Levine and L. Russell Brown copyrighted the song "Tie a Yellow Ribbon Round the Ole Oak Tree," which became a pop hit in early 1973 and sparked a lawsuit by Hamill, later dropped.

In 1975, the wife of a Watergate conspirator put out yellow ribbons when her husband was released from jail, and news coverage of that was noted and remembered by Penne Laingen, whose husband was U.S. ambassador to Iran in 1979 and one of the Iran hostages taken in the embassy on Nov. 4. Her yellow ribbon in his honor was written up in the Dec. 10, 1979, "Washington Post." When the hostage families organized as the Family Liaison Action Group (FLAG), they took the yellow ribbon as their symbol. The ribbons revived in the 1991 Gulf War and again during the 2003 wars in Afghanistan and Iraq.
yelp (v.): Old English gelpan (Anglian), gielpan (West Saxon) "to boast," from Proto-Germanic *gelpanan (cf. Old Saxon galpon, Old Norse gjalpa "to yelp," Old Norse gjalp "boasting," Old High German gelph "outcry"), from PIE root *ghel- "to cry out" (see yell). Related: Yelped; yelping.
yelp (n.): Old English gielp "boasting," from source of yelp (v.). Meaning "quick, sharp bark or cry" is attested from c.1500.
Yemen: southwestern region of Arabia, from Arabic Yemen, literally "the country of the south," from yaman "right side" (i.e., south side, if one is facing east). The right side regarded as auspicious, hence Arabic yamana "he was happy," literally "he went to the right," and hence the Latin name for the region in Roman times, Arabia Felix, lit, "Happy Arabia."
yen (n.1): Japanese monetary unit, 1875, from Japanese yen, from Chinese yuan "round, round object, circle, dollar."
yen (n.2): "sharp desire, hunger," 1906, earlier yin "intense craving for opium" (1876), from Chinese (Cantonese) yan "craving," or from a Beijing dialect word for "smoke." Reinforced in English by influence of yearn.
yenta (n.): "gossip, busybody," 1923, from Yente Telebende, comic strip gossip in 1920s-30s writing of Yiddish newspaper humorist B. Kovner (pen-name of Jacob Adler) in the "Jewish Daily Forward." It was a common Yiddish fem. proper name, altered from Yentl and said to be ultimately from Italian gentile "kind, gentle," earlier "noble, high-born" (see gentle).
yeoman (n.): c.1300, "attendant in a noble household," of unknown origin, perhaps a contraction of Old English iunge man "young man," or from an unrecorded Old English *geaman, equivalent of Old Frisian gaman "villager," from Old English -gea "district, village," cognate with Old Frisian ga, ge, from Proto-Germanic *gaujan.

Sense of "commoner who cultivates his land" is recorded from early 15c.; also the third order of fighting men (late 14c., below knights and squires, above knaves), hence yeomen's service "good, efficient service" (c.1600). Meaning "naval petty officer in charge of supplies" is first attested 1660s. Yeowoman first recorded 1852: "Then I am yeo-woman O the clumsy word!" [Tennyson, "The Foresters"]
yeomanry (n.): late 14c., from yeoman + -ry.
yep: by 1889, American English, variant of yes, altered for emphasis, or possibly influenced by nope.
yer: representing a dialectal or vulgar pronunciation of your, attested from 1814.
yes: Old English gise, gese "so be it!," probably from gea, ge "so" (see yea) + si "be it!," third person imperative of beon "to be" (see be). Originally stronger than simple yea. Used in Shakespeare mainly as an answer to negative questions. Yes-man is first recorded 1912, American English.
yeshiva (n.): "Orthodox Jewish college or seminary," 1851, from Hebrew yesibah "academy," literally "a sitting," from yashav "to sit."
yesterday (n.): Old English geostran dæg, from dæg "day" (see day) + geostran "yesterday," from Proto-Germanic *gestra- (cf. Old High German gestaron, German gestern "yesterday," Old Norse gær "tomorrow, yesterday," Gothic gistradagis "tomorrow"), originally "the other day" (reckoned from "today," either backward or forward), from PIE *ghes (cf. Sanskrit hyah, Avestan zyo, Persian di, Greek khthes, Latin heri, Old Irish indhe, Welsh doe "yesterday;" Latin hesternus "of yesterday").
yesteryear (n.): coined 1870 by Dante Gabriel Rossetti from yester(day) + year to translate French antan (from Vulgar Latin *anteannum "the year before") in a refrain by François Villon: Mais ou sont les neiges d'antan? which Rossetti rendered "But where are the snows of yesteryear?"
yet (adv.): Old English get, gieta "till now, thus far, earlier, at last, also," an Anglo-Frisian word (cf. Old Frisian ieta, Middle High German ieuzo), of unknown origin; perhaps connected to PIE pronomial stem *i- (see yon). The meaning in other Germanic languages is expressed by descendants of Proto-Germanic *noh- (cf. German noch), from PIE *nu-qe- "and now."
yeti: 1937, from Sherpa (Tibetan) yeh-teh "small manlike animal."
yew (n.): Old English iw, eow "yew," from Proto-Germanic *iwa-/*iwo- (cf. Middle Dutch iwe, Dutch ijf, Old High German iwa, German Eibe, Old Norse yr), from PIE *ei-wo- (cf. Old Irish eo, Welsh ywen "yew"), perhaps a suffixed form of *ei- "reddish, motley, yellow." OED says French if, Spanish iva, Medieval Latin ivus are from Germanic (and says Dutch ijf is from French); others posit a Gaulish ivos as the source of these. Lithuanian jeva likewise is said to be from Germanic. The tree symbolizes both death and immortality, being poisonous as well as long-lived.
Yggdrasil: great tree of the universe, 1770, from Old Norse ygdrasill, apparently from Yggr, a name of Odin + drasill "horse."
Yid: generally derogatory term for a Jew, 1874, from Yiddish use, where it is complimentary (see Yiddish).
Yiddish: 1875, from Yiddish yidish, from Middle High German jüdisch "Jewish" (in phrase jüdisch deutsch "Jewish-German"), from jude "Jew," from Old High German judo, from Latin Judaeus (see Jew). The English word has been re-borrowed in German as jiddisch.
yield (v.): Old English geldan (Anglian), gieldan (West Saxon) "to pay" (class III strong verb; past tense geald, past participle golden), from Proto-Germanic *geldanan "pay" (cf. Old Saxon geldan "to be worth," Old Norse gjaldo "to repay, return," Middle Dutch ghelden, Dutch gelden "to cost, be worth, concern," Old High German geltan, German gelten "to be worth," Gothic fra-gildan "to repay, requite").

Perhaps from PIE *ghel-to- "I pay," found only in Balto-Slavic and Germanic, unless Old Church Slavonic zledo, Lithuanian geliuoti are Germanic loan-words. Sense developed in English via use to translate Latin reddere, French rendre, and had expanded by c.1300 to "repay, return, render (service), produce, surrender." Related to Middle Low German and Middle Dutch gelt, Dutch geld, German Geld "money." Yielding in sense of "giving way to physical force" is recorded from 1660s.
yield (n.): Old English gield "payment, sum of money" (see yield (v.)); extended sense of "production" (as of crops) is first attested mid-15c. Earliest English sense survives in financial "yield from investments."
yikes: exclamation of alarm or surprise, by 1953; perhaps from yoicks, a call in fox-hunting, attested from c.1770. Yike "a fight" is slang attested from 1940, of uncertain connection.
yin: 1670s, from Chinese (Mandarin) "female, night, lunar."
yip: 1903, possibly from dialectal yip "to cheep like a bird" (early 19c.), from Middle English yippen (mid-15c.), of imitative origin.
yippee: interjection of pleasure, etc., 1920.
Yippie: 1968, acronym from fictitious "Youth International Party," modeled on hippie.
On December 31, 1967, Abbie [Hoffman], Jerry [Rubin], Paul Krassner, Dick Gregory, and friends decided to pronounce themselves the Yippies. (The name came first, then the acronym that would satisfy literal-minded reporters: Youth International Party.) [Todd Gitlin," The Sixties," 1987, p.235]
yo: as a greeting, 1859, but the word is attested as a sailor's or huntsman's utterance since early 15c. Modern popularity dates from World War II (when, it is said, it was a common response at roll calls) and seems to have been most intense in Philadelphia.
yo-yo (n.): 1915, apparently from a language of the Philippines. Registered as a trademark in Vancouver, Canada, in 1932, the year the first craze for them began (subsequent fads 1950s, 1970s, 1998). The toy itself is much older and was earlier known as bandalore (1824). Figurative sense of any "up-and-down movement" is first recorded 1932. Meaning "stupid person" is recorded from 1970. The verb in the figurative sense is attested from 1967.
yob: "a youth," 1859, back-slang from boy.
yod: 10th and smallest letter of the Hebrew alphabet.
yodel: 1827, from German jodeln, from dialectal German jo, an exclamation of joy, of imitative origin.
yoga: 1820, from Hindi yoga, from Sanskrit yoga-s, literally "union, yoking" (with the Supreme Spirit), from PIE root *yeug- "to join" (see jugular).
yogh: Middle English letter, c.1300; see Y. The name probably is identical with yoke (Middle English yogh) and so called because yoke began with a yogh.
yogi: "one who practices yoga," 1610s, from Hindi yogi, from Sanskrit yoga- (see yoga).