(informal) The London Underground

Anything that is hollow and cylindrical in shape.

An approximately cylindrical container, usually with a crimped end and a screw top, used to contain and dispense semiliquid substances.

(Australia, slang) A tin can containing beer.

(surfing) A wave which pitches forward when breaking, creating a hollow space inside.

(Canada, US, colloquial) A television. Compare cathode ray tube and picture tube.

(Scotland, slang) An idiot.

(transitive) To supply with, or enclose in, a tube.

To ride an inner tube.

(medicine, transitive, colloquial) To intubate.