From Longman Dictionary of Contemporary Englishbuttockbut‧tock /ˈbʌtək/ ●○○ noun [countable usually plural] HBHone of the fleshy parts of your body that you sit on
Examples from the Corpus
buttock• Of these elongated seats those contoured to give good support to the thighs and buttocks were most popular.• He lay stinking in the putrid morning sun, trousers pulled down around his buttocks.• He lay in a sort of mental haze until a feeling of restriction just below his buttocks penetrated his still slumbering state.• She kneads my buttocks, shaping them to her hands, spreading them apart.• She found it, pushed the door open, the light exposing rounded buttocks as she tumbled from the car.• I released her hand and grasped her firmly by the buttocks, small but ripe.Origin buttock Old English buttuc 