Source : WordNet®

rear end
     n : 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?" [syn: {buttocks}, {nates},
          {arse}, {butt}, {backside}, {bum}, {buns}, {can}, {fundament},
          {hindquarters}, {hind end}, {keister}, {posterior}, {prat},
          {rear}, {rump}, {stern}, {seat}, {tail}, {tail end}, {tooshie},
          {tush}, {bottom}, {behind}, {derriere}, {fanny}, {ass}]