yuck (2) Look up yuck at Dictionary.com
"laugh," 1938, yock, probably imitative.
yucky (adj.) Look up yucky at Dictionary.com
1970, from yuck (1) + -y (2). Related: Yuckiness.
Yugoslav (n.) Look up Yugoslav at Dictionary.com
1853, from Slav + Serbo-Croatian jugo- "south," comb. form of jug "south, south wind, noon," from Old Church Slavonic jugu "south, south wind, noon."
Yugoslavia Look up Yugoslavia at Dictionary.com
1929 (earlier the country was Kingdom of the Serbs, Croats, and Slovenes); from Yugoslav + -ia. The name vanished from the map in 2003.
yuk (n.) Look up yuk at Dictionary.com
"laughter, something evoking laughs," 1964, imitative; see yuck (2).
Yukon Look up Yukon at Dictionary.com
territory of northwestern Canada, named for the river, from Athabaskan, perhaps Koyukon yookkene or Lower Tanana yookuna, said to mean "big river."
yule (n.) Look up yule at Dictionary.com
Old English geol, geola "Christmas Day, Christmastide," from Old Norse jol (plural), a heathen feast, later taken over by Christianity, of unknown origin.

The Old English (Anglian) cognate giuli was the Anglo-Saxons' name for a two-month midwinter season corresponding to Roman December and January, a time of important feasts but not itself a festival. After conversion to Christianity it narrowed to mean "the 12-day feast of the Nativity" (which began Dec. 25), but was replaced by Christmas by 11c., except in the northeast (areas of Danish settlement), where it remained the usual word.

Revived 19c. by writers to mean "the Christmas of 'Merrie England.' " First direct reference to the Yule log is 17c. According to some sources, Old Norse jol was borrowed into Old French as jolif, hence Modern French joli "pretty, nice," originally "festive" (see jolly).
yuletide (n.) Look up yuletide at Dictionary.com
late 15c., from yule + tide.
yum (interj.) Look up yum at Dictionary.com
exclamation of pleasure, attested from 1878.
Yuma Look up Yuma at Dictionary.com
native people of Arizona, also their language, of the Yuman family, the name probably is from O'odham (Piman) yu'mi and represents the name the Piman peoples applied to the Yuma people.
yummy Look up yummy at Dictionary.com
"delicious," 1899, from baby talk. Yum-yum as an exclamation of pleasure is recorded from 1878.
yup Look up yup at Dictionary.com
1906, variant of yes.
yuppie (n.) Look up yuppie at Dictionary.com
1982, acronym from "young urban professional," ousting competition from yumpie (1984), from "young upward-mobile professional," and yap (1984), from "young aspiring professional." The word was felt as an insult by 1985.
yurt (n.) Look up yurt at Dictionary.com
"house or hut of the natives of north and central Asia," 1784, ultimately from Russian yurta, from a Turkic language and originally meaning "home, dwelling."
YWCA (n.) Look up YWCA at Dictionary.com
also Y.W.C.A., 1874, initialism (acronym) of Young Women's Christian Association.