Buttocks

Usually, buttocks.

(in humans) either of the two fleshy protuberances forming the lower and back part of the trunk.
(in animals) the rump.

Sometimes, buttocks. Nautical. the aftermost portion of a hull above the water line and in front of the rudder, merging with the run below the water line.
Contemporary Examples

Alan Cumming: The Truth About My Father Tim Teeman October 13, 2014
Do Cougar Couples Survive? Anneli Rufus September 28, 2011
I Want a Bigger Butt Stanley Crouch November 30, 2009
Florida Child Abuse Scandal: The Victim’s New Life Jacqui Goddard February 23, 2011
Texas Court Says Upskirt Photos Are Art Emily Shire September 19, 2014

Historical Examples

Sleep Walking and Moon Walking Isidor Isaak Sadger
Intestinal Ills Alcinous Burton Jamison
The Mother and Her Child William S. Sadler
The Buttoned Sky Geoff St. Reynard
Intestinal Ills Alcinous Burton Jamison

noun
either of the two large fleshy masses of thick muscular tissue that form the human rump See also gluteus related adjectives gluteal natal
the analogous part in some mammals
n.
n.

Read Also:

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adjective (informal) making one tighten the buttocks through extreme fear or embarrassment: buttock-clenching embarrassment
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sycamore (def 1). Historical Examples The Library of Work and Play: Gardening and Farming. Ellen Eddy Shaw The Library of Work and Play: Gardening and Farming. Ellen Eddy Shaw The Library of Work and Play: Gardening and Farming. Ellen Eddy Shaw The Principal Species of Wood: Their Characteristic Properties Charles H. (Charles Henry) Snow The […]
Buttonbush
a North American shrub, Cephalanthus occidentalis, of the madder family, having globular flower heads. Historical Examples The Mammals of Warren Woods, Berrien County, Michigan Lee Raymond Dice

Button-down
(of a shirt collar) having buttonholes so it can be buttoned to the body of the shirt. (of a shirt) having a button-down collar. (especially of attitudes, opinions, etc.) extremely conventional; unimaginative. Contemporary Examples Pizza Guy for President! Bryan Curtis January 12, 2011 Naftali Bennett Wants You! Don Futterman December 24, 2012 Teaching ‘The Great […]
Button-ear
a dog’s ear that folds forward completely.