Source : Webster's Revised Unabridged Dictionary (1913)

Canister \Can"is*ter\ (k[a^]n"[i^]s*t[~e]r), n. [L. canistrum a
   basket woven from reeds Gr. ?, fr. ka`nh, ka`nna reed; cf. F.
   canistre. See {Cane}, and {Canaster}.]
   1. A small basket of rushes, reeds, or willow twigs, etc.

   2. A small box or case for holding tea, coffee, etc.

   3. (Mil.) A kind of case shot for cannon, in which a number
      of lead or iron balls in layers are inclosed in a case
      fitting the gun; -- called also {canister shot}.

Source : WordNet®

canister
     n 1: a metallic cylinder packed with shot and used as ammunition
          in a firearm [syn: {case shot}, {canister shot}]
     2: metal container for storing dry foods such as tea or flour
        [syn: {cannister}, {tin}]