Merriam-Webster's Collegiate® Dictionary, 11th Edition
BOOTY
I. noun (plural booties)
Etymology: modification of Middle French butin, from Middle Low German būte exchange
Date: 15th century
plunder taken (as in war), a rich gain or prize, see: spoil
II. noun also bootie (plural booties)
Etymology: alteration of an English-based creole word, ultimately from Early Modern English *bottie buttocks, perhaps from 1bottom + -ie
Date: 1928
buttocks