Canister n. : A small basket of rushes, reeds, or willow twigs, etc.

Canister n. : A small box or case for holding tea, coffee, etc.

Canister n. : 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.

Example:
What is the best Canister filter for a 55 gallon tank?

Taxonomy
Canister, container, free encyclopedia, Greek, reed, metal canister, woven reeds, search, 35mm camera film, free dictionary, Latin, canistrum, earthenware, cane, shape, Gas containers, Canister shot, disambiguation pages.

Defination from the web:
canister (sometimes mis-spelled cannister) comes from Latin (canistrum = basket) or Greek (καναστρον = wicker basket, or earthenware container) ... Canister shot or case-shot, which were types of artillery rounds used in warfare as anti-personnel ammunition ...