rump 
/ˈrʌmp/ noun
plural rumps /ˈrʌmp/ noun 1 a [count] : the back part of an animal's body where the thighs join the hips
▪ a horse's/cow's rump
b [count, noncount] : a piece of meat that comes from the rump of a cow —called also rump steak 2 [count] humorous : the part of the body you sit on : bottom
▪ I slipped and fell on my rump. 3 [singular] chiefly Brit : the part of a group that remains after most of the members of that group have left or been forced to leave
▪ a horse's/cow's rump
b [count, noncount] : a piece of meat that comes from the rump of a cow —called also rump steak
▪ I slipped and fell on my rump.
