Source : Webster's Revised Unabridged Dictionary (1913)

Chum \Chum\, v. i. [imp. p. p. {Chummed}; p. pr. & vb. n.
   {Chumming}.]
   To occupy a chamber with another; as, to chum together at
   college. [U. S.]

Source : WordNet®

chumming
     See {chum}

chum
     n : a close friend who accompanies his buddies in their
         activities [syn: {buddy}, {brother}, {crony}, {pal}, {sidekick}]
     [also: {chumming}, {chummed}]