Webster's Revised Unabridged Dictionary · 1913

Bum

Bum (bum) , noun

[Contr. from bottom in this sense.]

The buttock. [Low] — Shakespeare

bum ({not transcribed}) , intransitive verb

[See Boom, v. i., to roar.]

To make murmuring or humming sound. — Jamieson
Collocations (1)
to bum around , to wander about idly or aimlessly.

bum (bum) , transitive verb

To borrow without intention of returning; to cadge; as, to bum a cigarette; to bum a cup of coffee; -- usually with inexpensive items as the object. [informal]

Bum , noun

A humming noise. — Halliwell