Anything that is hollow and cylindrical in shape.
The London Underground railway system, originally referred to the lower level lines that ran in tubular tunnels as opposed to the higher ones which ran in rectangular section tunnels. (Often the tube.)
A television. Compare cathode ray tube and picture tube.
A tin can containing beer.
An approximately cylindrical container, usually with a crimped end and a screw top, used to contain and dispense semiliquid substances.
An idiot.
A wave which pitches forward when breaking, creating a hollow space inside.
To supply with, or enclose in, a tube.
To intubate.
To ride an inner tube.