rump (n.) Look up rump at Dictionary.com
"hind-quarters, buttocks of an animal," mid-15c., from a Scandinavian source (cf. Danish, Norwegian rumpe, Swedish rumpa), cognate with Middle Dutch romp, German Rumpf "trunk, torso." Sense of "small remnant" derives from "tail" and is first recorded 1640s in reference to the English Rump Parliament (December 1648-April 1653).