Definition of rumps:
(n) :
The buttocks.
(n) :
The hindquarters of a four-legged mammal, not including its legs
(n) :
A cut of meat from the rump of an animal.
(v) :
(transitive) To turn one's back on, to show one's (clothed) backside to, as a sign of disrespect.
(v) :
(somewhat vulgar, slang) To fuck. (Compare bum (verb).)
(n) :
A remnant, as in Rump Parliament.