Webster's Revised Unabridged Dictionary · 1913

Chum

Chum (chum) , noun

[Perh. a contraction from comrade or chamber fellow: compare also Anglo-Saxon cuma a comer, guest.]

A roommate, especially in a college or university; an old and intimate friend.
Collocations (1)
New chum , a recent immigrant. [Australia]

Chum , intransitive verb

To occupy a chamber with another; as, to chum together at college. [United States]

Chum , noun

Chopped pieces of fish used as bait. [United States]