rump
noun
[ rʌmp ]
• the hind part of the body of a mammal or the lower back of a bird.
• "the harrier is distinguished by its prominent white rump"
• a small or unimportant remnant of something originally larger.
• "once the profitable enterprises have been sold the unprofitable rump will be left"
Origin:
late Middle English: probably of Scandinavian origin; compare with Danish and Norwegian rumpe ‘backside’.