"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.
y'all
yacht
yack
yadda-yadda
yah
yahoo
Yahtzee
Yahweh
yak
Yakima
yakuza