rump


rump (http://definr.com/rump)

     n 1: the part of a quadruped that corresponds to the human
          buttocks [syn: hindquarters, croup, croupe]
     2: fleshy hindquarters; behind the loin and above the round
     3: the fleshy part of the human body that you sit on [syn: buttocks,
         nates, arse, butt, backside, bum, buns, can,
         fundament, hindquarters, hind end, keister, posterior,
         prat, rear, rear end, stern, seat, tail, {tail
        end}, tooshie, tush, bottom, behind, derriere, fanny,
         ass]