What is the meaning of posterior?

noun

• The fleshy part of the human body that you sit on.
  • usage: "he deserves a good kick in the butt"; "are you going to sit on your fanny and do nothing"
  • synonyms: buttocks, nates, arse, butt, backside, bum, buns, can, fundament, hindquarters, hind end, keister, prat, rear, rear end, rump, stern, seat, tail, tail end, tooshie, tush, bottom, behind, derriere, fanny, ass
• A tooth situated at the back of the mouth.
  • synonyms: back tooth

adjective

• Located at or near or behind a part or near the end of a structure.
• Coming at a subsequent time or stage.
  • usage: "without ulterior argument"; "the mood posterior to"
  • synonyms: later, ulterior