buttocks
Concise Oxford English Dictionary © 2008 Oxford University Press:
buttock/ˈbʌtək/
▶noun either of the two round fleshy parts of the human body that form the bottom.
'buttocks' also found in these Oxford entries:
arse
- ass
- backside
- bahookie
- bascule bridge
- bippy
- bottom
- breech
- breech birth
- bum
- bun
- callipygian
- cheek
- derrière
- duff
- fanny
- fundament
- ham
- heinie
- hip
- keister
- moon
- natal
- nates
- patootie
- posterior
- prat
- pratfall
- quoit
- rass
- rear
- recoil
- rump
- seat
- sit
- sitz bath
- spank
- squat
- steatopygia
- tail
- tush
- tutu
- wedgie
