What is the meaning of Canister?

A cylindrical or rectangular container usually of lightweight metal, plastic, or laminated pasteboard used for holding a dry product (as tea, crackers, flour, matches).

Any of various cylindrical metal receptacles usually with a removable close-fitting top.

A special short-range antipersonnel projectile consisting of a casing of light metal, loaded with preformed submissiles such as flechettes or steel balls. The casing is designed to open just beyond the muzzle of the weapon, dispersing the submissiles.

A projectile component containing colored or screening smoke or riot control agent composition.

A component of canister-type protective masks containing a mechanical filter and chemical filling to filter, neutralize and/or absorb toxic chemical, biological and radiological agents.

Part of a windmill that connects the sails to the windshaft.

A person's head.

To pack into a canister.

Source: wiktionary.org