rear_end
1. [ noun ] the fleshy part of the human body that you sit on
Synonyms: seat ass bottom tail buttocks behind stern hindquarters fundament hind_end keister bum backside posterior prat buns rear tail_end tooshie tush rump can derriere fanny butt nates arse
Examples:

"he deserves a good kick in the butt" "are you going to sit on your fanny and do nothing?"

Related terms: body_part torso
Similar spelling:   rear-end
  rear_window
  reorient