Definitions for keisterˈki stər
Random House Webster's College Dictionary
the buttocks; rump.
Category: Common Vocabulary, Status (usage)
Origin of keister:
1880–85; earlier, as argot, handbag, suitcase, safe; of obscure orig.
buttocks, nates, arse, butt, backside, bum, buns, can, fundament, hindquarters, hind end, keister, posterior, prat, rear, rear end, rump, stern, seat, tail, tail end, tooshie, tush, bottom, behind, derriere, fanny, ass(noun)
the fleshy part of the human body that you sit on
"he deserves a good kick in the butt"; "are you going to sit on your fanny and do nothing?"