posterior
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?
Synonym: keister, nates, prat, rear, rear end, rump, seat, stern, tail, tail end, tooshie, tush, hindquarters, hind end, fundament, arse, ass, backside, behind, bottom, bum, buns, butt, buttocks, can, derriere, fanny
noun.
a tooth situated at the back of the mouth
Synonym: back tooth
adj.
located at or near or behind a part or near the end of a structure
adj.
coming at a subsequent time or stage
without ulterior argument|the mood posterior to
Synonym: later, ulterior
Antonym: anterior