Online Etymology Dictionary

yins (pron.): "you people, you-all," contracted from U.S. dialectal you-uns, for you-ones (see you, also see y'all); first noted 1810 in Ohio. Also yinz; now considered a localism in Pittsburgh, Pa.
yip (v.): 1891, possibly from dialectal yip "to cheep like a bird" (early 19c.), from Middle English yippen (mid-15c.), of imitative origin. As a noun from 1896.
yippee (interj.): interjection of pleasure, exultation, etc., 1920; perhaps an extension and modification of hip (interj.).
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]
YMCA (n.): also Y.M.C.A., 1868, initialism (acronym) of Young Men's Christian Association.
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 (1802), a word of obscure origin, "but it was from American contact in the Philippines that the first commercial development was established" [Century Dictionary]. 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 (n.): "a youth," 1859, British English, back-slang from boy. By 1930s with overtones of "hooligan, lout." Related: extended form yobbo.
yod (n.): 10th and smallest letter of the Hebrew alphabet (compare jot, iota).
yodel (v.): "sing by sudden changing to and from falsetto," 1827, from German jodeln, from dialectal German jo, an exclamation of joy, of imitative origin. As a noun from 1849.
yoga (n.): 1820, from Hindi yoga, from Sanskrit yoga-s, literally "union, yoking" (with the Supreme Spirit), from PIE root *yeug- "to join" (see jugular). Related: Yogic.
yogh (n.): Middle English letter (Ȝ), c. 1300; see Y. The name probably is identical with yoke (Middle English yogh) and so called because yoke began with a yogh.
yogi (n.): "one who practices yoga," 1610s, from Hindi yogi, from Sanskrit yoga- (see yoga). Related: Yogism.
yogurt (n.): also yoghurt, 1620s, a mispronunciation of Turkish yogurt, in which the -g- is a "soft" sound, in many dialects closer to an English "w." The root yog means roughly "to condense" and is related to yogun "intense," yogush "liquify" (of water vapor), yogur "knead."
yok (n.): slang, "gentile, non-Jew," pejorative, 1920, from Yiddish, where it is back slang, a reversed and altered form of goy.
yoke (n.): Old English geoc "contrivance for fastening a pair of draft animals," earlier geoht "pair of draft animals" (especially oxen), from Proto-Germanic *yukam (source also of Old Saxon juk, Old Norse ok, Danish aag, Middle Dutch joc, Dutch juk, Old High German joh, German joch, Gothic juk "yoke"), from PIE root *yeug- "to join" (see jugular). Figurative sense of "heavy burden, oppression, servitude" was in Old English.
yoke (v.): Old English geocian "to yoke, join together," from yoke (n.). Related: Yoked; yoking.
yokel (n.): 1812, perhaps from dialectal German Jokel, disparaging name for a farmer, originally diminutive of Jakob. Or perhaps from English yokel, dialectal name for "woodpecker."
yolk (n.): Old English geolca, geoloca "yolk," literally "the yellow part," from geolu "yellow" (see yellow (adj.)). Formerly also spelled yelk.
Yom Kippur: Jewish holiday, 1854, from Mishnaic Hebrew yom kippur (in Biblical Hebrew, yom kippurim), literally "day of atonement," from yom "day" + kippur "atonement, expiation."
yon (adj., pron.): Old English geon "that (over there)," from Proto-Germanic *jaino- (source also of Old Frisian jen, Old Norse enn, Old High German ener, Middle Dutch ghens, German jener, Gothic jains "that, you"), from PIE pronominal stem *i- (source also of Sanskrit ena-, third person pronoun, anena "that;" Latin idem "the same," id "it, that one;" Old Church Slavonic onu "he;" Lithuanian ans "he"). As an adverb from late 15c., a shortening of yonder.
yond (adv., prep.): Old English geond "beyond, yonder," related to geon (see yon).
yonder (adv.): "within sight but not near," c. 1300, from Old English geond "throughout, up to, as far as" (see yond) + comparative suffix -er (2). Cognate with Middle Low German ginder, Middle Dutch gender, Dutch ginder, Gothic jaindre. Now replaced except in poetic usage by ungrammatical that.
yoni (n.): 1799, from Sanskrit, "female sexual principle as an object of veneration," literally "vulva, womb."
yoo-hoo (interj.): exclamation to call attention, by 1913.
yore (adv.): Old English geara "of yore, formerly, in former times," literally "of years," originally adverbial genitive plural of gear (see year), and used without of. As a noun from mid-14c.
York: city in northern England, Old English Eoforwic, earlier Eborakon (c. 150), an ancient Celtic name, probably meaning "Yew-Tree Estate," but Eburos may also be a personal name. Related: Yorkist; Yorkish; Yorker. Yorkshire pudding is recorded from 1747; Yorkshire terrier first attested 1872; short form Yorkie is from 1950.
Yoruba: west Nigerian people, also the name of their language.
Yosemite: from Southern Sierra Miwok /yohhe'meti/ "they are killers." "[E]vidently a name given to the Indians of the valley by those outside it." [Bright]
you (pron.): Old English eow, dative and accusative plural of þu (see thou), objective case of ge, "ye" (see ye), from Proto-Germanic *juz-, *iwwiz (source also of Old Norse yor, Old Saxon iu, Old Frisian iuwe, Middle Dutch, Dutch u, Old High German iu, iuwih, German euch), from PIE *yu, second person (plural) pronoun.

Pronunciation of you and the nominative form ye gradually merged from 14c.; the distinction between them passed out of general usage by 1600. Widespread use of French in England after 12c. gave English you the same association as French vous, and it began to drive out singular nominative thou, originally as a sign of respect (similar to the "royal we") when addressing superiors, then equals and strangers, and ultimately (by c. 1575) becoming the general form of address. Through 13c. English also retained a dual pronoun ink "you two; your two selves; each other."
young (adj.): Old English geong "youthful, young; recent, new, fresh," from Proto-Germanic *juwunga- (source also of Old Saxon and Old Frisian jung, Old Norse ungr, Middle Dutch jonc, Dutch jong, Old High German and German jung, Gothic juggs), from PIE *yuwn-ko-, suffixed form of root *yeu- "vital force, youthful vigor" (source also of Sanskrit yuva "young," Latin juvenis "young," Lithuanian jaunas, Old Church Slavonic junu, Russian junyj "young," Old Irish oac, Welsh ieuanc "young").

From c. 1830-1850, Young France, Young Italy, etc., were loosely applied to "republican agitators" in various monarchies; also, especially in Young England, Young America, used generally for "typical young person of the nation." For Young Turk, see Turk.
young (n.): "young animals collectively, offspring," late 15c., from young (adj.).
youngster (n.): 1580s, from young + -ster. Earlier was youngling, from Old English geongling.
younker: c. 1500, "young nobleman," from Middle Dutch jonckher (Dutch jonker), from jonc "young" (see young (adj.)) + here "lord, master" (see Herr). Compare junker.
your: Old English eower, possessive pronominal adjective, genitive of ge "ye" (see ye), from Proto-Germanic base of you. Cognate with Old Saxon iuwar, Old Frisian iuwer, Old Norse yðvarr, Old High German iuwer, German euer, Gothic izwar "your." Used in titles of honor by mid-14c.
yourn (pron.): dialectal possessive pronoun from your, attested from late 14c. See her.
yours (pron.): absolutive form of your, c. 1300, on model of his, ours, etc. Yours truly "myself" is from 1833, from the common subscription of letters.
It is difficult to say what will succeed, and still more to pronounce what will not. I am at this moment in that uncertainty (on our own score,) and it is no small proof of the author's powers to be able to charm and fix a mind's attention on similar subjects and climates in such a predicament. That he may have the same effect upon all his readers is very sincerely the wish, and hardly the doubt, of yours truly,
"B."
[Lord Byron to John Murray, Dec. 4, 1813]
yourself: by early 14c., from your + self. Plural yourselves first recorded 1520s.
youse: dialectal inflection of you, 1876, not always used in plural senses.
youth (n.): Old English geoguð "youth; young people, junior warriors; young of cattle," related to geong "young," from Proto-Germanic *jugunthi- (source also of Old Saxon juguth, Old Frisian jogethe, Middle Dutch joghet, Dutch jeugd, Old High German jugund, German Jugend, Gothic junda "youth"), from suffixed form of PIE root *yeu- "vital force, youthful vigor" (see young (adj.)) + Proto-Germanic abstract noun suffix *-itho (see -th (2)).

According to OED, the Proto-Germanic form apparently was altered from *juwunthiz by influence of its contrast, *dugunthiz "ability" (source of Old English duguð). In Middle English, the medial -g- became a yogh, which then disappeared.
They said that age was truth, and that the young
Marred with wild hopes the peace of slavery
[Shelley]
youthful (adj.): 1560s, from youth + -ful. Old English had geoguðlic. Other words formerly used in the same sense were youthlike, youthly, youthsome, youthy. Related: Youthfulness.
yow: exclamation, with various meanings, mid-15c.
yowl (v.): c. 1200, yuhelen, probably of imitative origin (compare jubilant). Related: Yowled; yowling. The noun is recorded from mid-15c.
yowza: colloquial form of yes, sir, 1934, popularized by U.S. bandleader and radio personality Ben "The Old Maestro" Bernie (1891-1943).
ytterbium (n.): metallic rare-earth element, 1879, coined in Modern Latin by Swedish chemist Carl Gustaf Mosander (1797-1858) from Ytterby, name of a town in Sweden where mineral containing it was found. With metallic element ending -ium.
yttrium: metallic rare-earth element, 1866, coined in Modern Latin by Swedish chemist Carl Gustaf Mosander (1797-1858) from Ytterby, name of a town in Sweden where mineral containing it was found. With metallic element ending -ium.
yuan (n.): Chinese unit of currency introduced 1914, from Chinese yuan "round, round object, circle."
Yucatan: said to be from a local word meaning "massacre." Related: Yucatecan.
yucca (n.): Central and South American name for the cassava plant, 1550s, from Spanish yuca, juca (late 15c.), probably from Taino, native language of Haiti.
yuck (1): exclamation of disgust, 1966, origin perhaps echoic (compare Newfoundland slang yuck "to vomit," 1963; U.S. slang yuck "despised person," 1943; provincial English yuck "the itch, mange, scabies"). Variant yech is by 1969.