The buttocks.
Okay, everyone sit on your bum and try and touch your toes.
The anus.
To sodomize; to engage in anal sex.
An expression of annoyance.
(sometimes derogatory) A homeless person, usually a man.
A lazy, incompetent, or annoying person, usually a man.
Fred is becoming a bum - he's not even bothering to work more than once a month.
A player or racer who often performs poorly.
Trade him to another team, he's a bum!
A drinking spree.
To ask someone to give one (something) for free; to beg for something.
Can I bum a cigarette off you?
To stay idle and unproductive, like a hobo or vagabond; to loiter.
I think I'll just bum around downtown for awhile until dinner.
To wet the end of a marijuana cigarette (spliff).
Of poor quality or highly undesirable.
bum note
Unfair.
bum deal
Injured and without the possibility of full repair, defective.
I can't play football anymore on account of my bum knee.
Unpleasant or unhappy.
He had a bum trip on that mescaline.
To depress; to make unhappy.
A humming noise.
To make a murmuring or humming sound.
A bumbailiff.