the GNU version of the Collaborative International Dictionary of English
noun-plural. the fleshy part of the human body at the back of the hip, on which a person sits.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. the fleshy part of the human body that you sit on
Word Usage
"The treatments seem reasonable, although the page about checking babies for foot problems by inspecting the number and even-ness of the creases under their buttocks is a little strange."