Online Etymology Dictionary

Y: a late-developing letter in English. Called ipsilon in German, upsilon in Greek, the English name is of obscure origin. The sound at the beginning of yard, yes, yield, etc. is from Old English words with initial g- as in got and y- as in yet, which were considered the same sound and often transcribed as Ȝ, known as yogh. The system was altered by French scribes, who brought over the continental use of -g- and from the early 1200s used -y- and sometimes -gh- to replace Ȝ. As short for YMCA, etc., by 1915.
y'all (pron.): by 1879, U.S. dialect abbreviation of you all (see you, and compare yins).
Children learn from the slaves some odd phrases ... as ... will you all do this? for, will one of you do this? ["Arthur Singleton" (Henry C. Knight), "Letters from the South and West," 1824]
We-all for "us" is attested by 1865; we-uns by 1864. Who-all attested from 1899.
y-: perfective prefix, in yclept, etc.; a deliberate archaism, introduced by Spenser and his imitators, representing an authentic Middle English prefix y-, earlier i-, from Old English ge-, originally meaning "with, together" but later a completive or perfective element, from Proto-Germanic *ga- "together, with" (also a collective and intensive prefix), from PIE *kom "beside, near, by, with" (cognate with Sanskrit ja-, Latin com-, cum-; see com-). It is still living in German and Dutch ge-, and survives, disguised, in some English words (such as alike, aware, handiwork).

Among hundreds of Middle English words it formed are yfallen, yhacked ("completely hacked," probably now again useful), yknow, ymarried, ywrought.
yacht (n.): 1550s, yeaghe "a light, fast-sailing ship," from Norwegian jaght or early Dutch jaght, both from Middle Low German jacht, shortened form of jachtschip "fast pirate ship," literally "ship for chasing," from jacht "chase," from jagen "to chase, hunt," from Old High German jagon, from Proto-Germanic *yago-, from PIE root *yek- (2) "to hunt" (source also of Hittite ekt- "hunting net"). Related: Yachting; yachtsman.
yack (v.): also yak, "to talk, to chatter," 1950, slang, probably short for yackety-yacking "talk" (1947), probably echoic (compare Australian slang yacker "talk, conversation," 1882). Related: Yacked; yacking.
yadda-yadda: "and so on," 1990s, of echoic origin (compare yatata "talk idly, chatter," 1940s; and yatter "to talk incessantly or idly," 1825).
yah (interj.): exclamation of defiance or dismissal, from 1812. Extended form yah-boo by 1910.
yahoo (n.): "a brute in human form," 1726, from the race of brutish human creatures in Swift's "Gulliver's Travels." "A made name, prob. meant to suggest disgust" [Century Dictionary]. "Freq. in mod. use, a person lacking cultivation or sensibility, a philistine; a lout; a hooligan" [OED]. The internet search engine so called from 1994.
Yahtzee (n.): dice game, 1957, proprietary (E.S. Lowe Co., N.Y.), apparently based on yacht.
Yahweh: 1869, hypothetical reconstruction of the tetragrammaton YHWH (see Jehovah), based on the assumption that the tetragrammaton is the imperfective of Hebrew verb hawah, earlier form of hayah "was," in the sense of "the one who is, the existing."
yak (n.): "wild ox of central Asia," 1795, from Tibetan g-yag "male yak." Attested in French from 1791.
yak (v.): "laugh," 1938, variant of yuck (2); "talk idly," 1950, variant of yack. Related: Yakked; yakking.
Yakima: Native American people of Washington State, 1852, perhaps from Sahaptin /iyakima/ "pregnant women."
yakuza (n.): traditional Japanese organized crime cartel, literally "eight-nine-three" (ya, ku, sa) the losing hand in the traditional baccarat-like Japanese card game Oicho-Kabu. The notion may be "good for nothing," or "bad luck" (such as that suffered by someone who runs afoul of them), or it may be a reference to the fact that a player who draws this hand requires great skill to win.
Yale: university in New Haven, Connecticut, U.S., founded 1701 as Collegiate School, renamed 1718 in honor of a gift from British merchant-philanthropist Elihu Yale (1649-1721). As a kind of lock, 1854, invented by U.S. mechanic Linus Yale Jr. (1821-1868). The surname is Welsh, from ial, and means "dweller at the fertile upland." Related: Yalie.
yam (n.): 1580s, igname (current form by 1690s), from Portuguese inhame or Spanish igname, from a West African language (compare Fulani nyami "to eat;" Twi anyinam "species of yam"); the word in American and Jamaican English probably is directly from West African sources. The Malay name is ubi, whence German öbiswurzel.
yammer (v.): late 15c., "to lament," probably from Middle Dutch jammeren and cognate Middle English yeoumeren, "to mourn, complain," from Old English geomrian "to lament," from geomor "sorrowful," probably of imitative origin. Cognate with Old Saxon jamar "sad, sorrowful," German Jammer "lamentation, misery." Meaning "to make loud, annoying noise" is attested from 1510s. Related: Yammered; yammering.
yang (n.): masculine or positive principle in Chinese philosophy, 1670s, from Mandarin yang, said to mean "male, daylight, solar," or "sun, positive, male genitals."
yank (v.): "to pull, jerk," 1822, Scottish, of unknown origin. Related: Yanked; yanking. The noun is 1818 in sense of "sudden blow, cuff;" 1856 (American English) as "a sudden pull."
Yank (n.): abbreviated form of Yankee, 1778.
Yankee (n.): 1683, a name applied disparagingly by Dutch settlers in New Amsterdam (New York) to English colonists in neighboring Connecticut. It may be from Dutch Janke, literally "Little John," diminutive of common personal name Jan; or it may be from Jan Kes familiar form of "John Cornelius," or perhaps an alteration of Jan Kees, dialectal variant of Jan Kaas, literally "John Cheese," the generic nickname the Flemings used for Dutchmen.
[I]t is to be noted that it is common to name a droll fellow, regarded as typical of his country, after some favorite article of food, as E[nglish] Jack-pudding, G[erman] Hanswurst ("Jack Sausage"), F[rench] Jean Farine ("Jack Flour"). [Century Dictionary, 1902, entry for "macaroni"]
Originally it seems to have been applied insultingly to the Dutch, especially freebooters, before they turned around and slapped it on the English. A less-likely theory (attested by 1832) is that it represents some southern New England Algonquian language mangling of English. In English a term of contempt (1750s) before its use as a general term for "native of New England" (1765); during the American Revolution it became a disparaging British word for all American natives or inhabitants. Contrasted with southerner by 1828. Shortened form Yank in reference to "an American" first recorded 1778. Latin-American form Yanqui attested in English by 1914 (in Mexican Spanish by 1835).
The rule observed in this country is, that the man who receives that name [Yankee] must come from some part north of him who gives it. To compensate us for giving each other nicknames, John Bull "lumps us all together," and calls us all Yankees. ["Who is a Yankee?" Massachusetts Spy, June 6, 1827]
Yankee Doodle (n.): popular tune of the American Revolution, apparently written c. 1755 by British Army surgeon Dr. Richard Schuckburgh while campaigning with Amherst's force in upper New York during the French and Indian War. The original verses mocked the colonial troops (see Yankee) serving alongside the regulars, and the Doodle element might have been, or hinted at, the 18c. slang term for "penis." The song naturally was popular with British troops in the colonies during the Revolutionary War, but after the colonials began to win skirmishes with them in 1775, they took the tune as a patriotic prize and re-worked the lyrics. The current version seems to have been written in 1776 by Edward Bangs, a Harvard sophomore who also was a Minuteman.
yap (v.): 1660s, "bark as a (small) dog," earlier as a noun, "yapping dog" (c. 1600), probably of imitative origin. Compare verb yamph in same sense (1718). Originally in reference to dog sounds; meaning "to talk idle chatter" is first recorded 1886. Related: Yapped; yapping. As a noun, 1826 in reference to the sound; 1900, American English slang as "mouth."
yappy (adj.): 1909, from yap + -y (2).
yar: growling sound, imitative, attested from c. 1300.
Yarborough (n.): in bridge/whist, a hand with no card above a nine, 1874, said to be so called for an unnamed Earl of Yarborough who bet 1,000 to 1 against its occurrence.
yard (n.1): "patch of ground around a house," Old English geard "fenced enclosure, garden, court; residence, house," from Proto-Germanic *gardaz (source also of Old Norse garðr "enclosure, garden, yard;" Old Frisian garda, Dutch gaard, Old High German garto, German Garten "garden;" Gothic gards "house," garda "stall"), from PIE *ghor-to-, suffixed form of root *gher- (1) "to grasp, enclose," with derivatives meaning "enclosure" (source also of Old English gyrdan "to gird," Sanskrit ghra- "house," Albanian garth "hedge," Latin hortus "garden," Phrygian -gordum "town," Greek khortos "pasture," Old Irish gort "field," Breton garz "enclosure, garden," and second element in Latin cohors "enclosure, yard, company of soldiers, multitude").

Lithuanian gardas "pen, enclosure," Old Church Slavonic gradu "town, city," and Russian gorod, -grad "town, city" belong to this group, but linguists dispute whether they are independent developments or borrowings from Germanic. As "college campus enclosed by the main buildings," 1630s. Shipyard is from c. 1700. In railway usage, "ground adjacent to a train station or terminus, used for switching or coupling trains," 1827. Yard sale is attested by 1976.
yard (n.2): measure of length, Old English gerd (Mercian), gierd (West Saxon) "rod, staff, stick; measure of length," from West Germanic *gazdijo, from Proto-Germanic *gazdjo- "stick, rod" (source also of Old Saxon gerda, Old Frisian ierde, Dutch gard "rod;" Old High German garta, German gerte "switch, twig," Old Norse gaddr "spike, sting, nail"), from PIE root *ghazdh-o- "rod, staff, pole" (source also of Latin hasta "shaft, staff"). The nautical yard-arm retains the original sense of "stick."

Originally in Anglo-Saxon times a land measure of roughly 5 meters (a length later called rod, pole, or perch). Modern measure of "three feet" is attested from late 14c. (earlier rough equivalent was the ell of 45 inches, and the verge). In Middle English and after, the word also was a euphemism for "penis" (as in "Love's Labour's Lost," V.ii.676). Slang meaning "one hundred dollars" first attested 1926, American English. Middle English yerd (Old English gierd) also was "yard-land, yard of land," a varying measure but often about 30 acres or a quarter of a hide.
yard-arm (n.): also yardarm, 1550s, from yard (n.2) in the nautical sense (attested from Old English) + arm (n.1). In 19c. British naval custom, it was permissible to begin drinking when the sun was over the yard-arm.
yardage (n.): "aggregate number of yards," 1900 in sports, from yard (n.2) + -age.
yardbird (n.): "convict," 1956, from yard (n.1) + bird (n.1), from the notion of prison yards; earlier it meant "basic trainee" (World War II armed forces slang).
yardstick (n.): also yard-stick, 1797, from yard (n.2) + stick (n.).
yare (adj.): "ready, prepared," Old English gearo "ready, prepared, equipped," from gearwian "to equip, prepare" (related to gearwe "clothing, dress") from Proto-Germanic *garwjan "to make, prepare, equip, ready, complete" (see gear (n.)). Cognate with German gar, Dutch gaar. Related: Yarely.
yarmulke (n.): 1903, from Yiddish yarmulke, from Polish jarmułka, originally "a skullcap worn by priests," perhaps ultimately from Medieval Latin almutia "cowl, hood."
yarn (n.): Old English gearn "spun fiber, spun wool," from Proto-Germanic *garnan (source also of Old Norse, Old High German, German garn, Middle Dutch gaern, Dutch garen "yarn"), from PIE root *ghere- "intestine, gut, entrail" (source also of Old Norse gorn "gut," Sanskrit hira "vein; entrails," Latin hernia "rupture," Greek khorde "intestine, gut-string," Lithuanian zarna "gut"). The phrase to spin a yarn "to tell a story" is first attested 1812, from a sailors' expression, on notion of telling stories while engaged in sedentary work such as yarn-twisting.
yarrow (n.): plant, also known as milfoil, Old English gearwe "yarrow," from Proto-Germanic *garwo (source also of Middle Dutch garwe, Old High German garawa, German Garbe), perhaps from a source akin to the root of yellow (adj.).
yaw (v.): "to fall away from the line of a course," 1580s (as a noun 1540s), perhaps ultimately from Old Norse jaga, Old Danish jæge "to drive, chase," from Middle Low German jagen (see yacht).
yawl (n.): type of ship's boat, 1660s, apparently from Middle Low German jolle or Dutch jol "a Jutland boat" (according to a 1708 source), of uncertain origin. Also borrowed into French (yole), Italian (jolo), Russian (yal).
yawn (v.): c. 1300, yenen, yonen, from Old English ginian, gionian "open the mouth wide, yawn, gape," from Proto-Germanic *gin- (source also of Old Norse gina "to yawn," Dutch geeuwen, Old High German ginen, German gähnen "to yawn"), from PIE *ghai- "to yawn, gape" (source also of Old Church Slavonic zijajo "to gape," Lithuanian žioju, Czech zivati "to yawn," Greek khainein, Latin hiare "to yawn, gape," Sanskrit vijihite "to gape, be ajar"). Modern spelling is from 16c. Related: Yawned; yawning.
yawn (n.): "act of yawning," 1690s, from yawn (v.). Meaning "boring thing" is attested from 1889.
yawner (n.): 1680s, agent noun from yawn (v.). Meaning "boring thing" is 1942, American English colloquial (yawn (n.) in this sense is attested from 1889).
yawp (v.): c. 1300, yolpen, probably echoic variant of yelpen (see yelp). Related: Yawped; yawping. The noun, in reference to speech, is recorded from 1835, now used chiefly in conscious echo of Whitman (1855).
yaws (n.): contagious skin disease, 1670s, from Carib yaya, the native name for it.
yay: "this," as in yay big "this big," 1950s, perhaps from yea "yes" in its sense of "even, truly, verily." "a sort of demonstrative adverb used with adjectives of size, height, extent, etc., and often accompanied by a hand gesture indicating size" [DAS].
yclept: Old English gicliopad; from y- + past participle of cleopian, cpipian "to speak, call; summon, invoke; implore" (see clepe).
ye (pron.): Old English ge, nominative plural of 2nd person pronoun þu (see thou); cognate with Old Frisian ji, Old Saxon gi, Middle Dutch ghi, Dutch gij. Cognate with Lithuanian jus, Sanskrit yuyam, Avestan yuzem, Greek hymeis.

Altered, by influence of we, from an earlier form that was similar to Gothic jus "you (plural)" (see you). The -r- in Old Norse er, German ihr probably is likewise from influence of their respective 1st person plural pronouns (Old Norse ver, German wir).
ye (article): old or quaintly archaic way of writing the, in which the -y- is a 16c. graphic alteration of þ, an Old English character (generally called "thorn," originally a Germanic rune; see th) that represented the -th- sound (as at the beginning of thorn). The characters for -y- and -þ- so closely resembled each other in Old English and early Middle English handwriting that a dot had to be added to the -y- to keep them distinct. In late 15c., early printers in English, whose types were founded on the continent, did not have a þ in their sets, so they substituted y as the letter that looked most like it when setting type. But in such usages it was not meant to be pronounced with any of the sounds associated with -y-, but still as "-th-." Ye for the (and yt for that) continued in manuscripts through 18c. Revived 19c. as a deliberate antiquarianism; the Ye Olde _____ construction was being mocked by 1896.
yea (adv.): Old English gea (West Saxon), ge (Anglian) "so, yes," from Proto-Germanic *ja-, *jai-, a word of affirmation (source also of German, Danish, Norwegian, Swedish ja), from PIE *yam-, from pronominal stem *i- (see yon). As a noun, "affirmation, affirmative vote," from early 13c.
yeah: American English, colloquial, by 1863, from drawling pronunciation of yes.
yean (v.): Old English eanian "to bring forth" (young), especially in reference to sheep or goats, from Proto-Germanic *aunon (cognate with Dutch oonen), from PIE *agwh-no- "lamb" (source also of Greek amnos "lamb," Latin agnus, Old Church Slavonic agne, Old Irish uan, Welsh oen). Yeanling "young lamb, kid" is recorded from 1630s.