This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. Informal The buttocks; the rump.

n. The side of something that is opposite the front.

n. The buttocks.

n. The hinder part, posteriors, or rump of a person or animal.

n. The back part or aspect of anything; the part opposite to the front, or behind that which is presented to a spectator.

n. Specifically The hind part of an animal; the rump: often (vulgarly) in the plural.

n. The back premises, back yard, or out-buildings attached to a dwelling; also, the privy.

n. the side of an object that is opposite its front

n. the fleshy part of the human body that you sit on

"Wearing pants with words across the backside is a stumbling block."

body part   

buttocks   

buttock    arse    rump    torso    haunch    redhead    thigh    butt    calve    roundness