backside

名词 backside:

1. the side of an object that is opposite its front
   同义词：rear, back end
2. the fleshy part of the human body that you sit on
   同义词：buttocks, nates, arse, butt, bum, buns, can, fundament, hindquarters, hind end, keister, posterior, prat, rear, rear end, rump, stern, seat, tail, tail end, tooshie, tush, bottom, behind, derriere, fanny, ass

1. Get off your backside and do some work!
   别老坐著，干点儿实事！

back.side

n.Informal （名词）【非正式用语】
The buttocks; the rump.
臀部；尾部