noun

1. 1. a hollow cylinder or pipe of metal, glass, rubber, etc., usually long in proportion to its diameter, used for conveying fluids, etc.
   2. an instrument, part, organ, etc. resembling a tube bronchial tubes, eustachian tubes
   3. a fallopian tube: usually used in pl.
2. a rubber casing inflated with air and used, esp. formerly, with an outer casing to form an automotive tire
3. a cylindrical container made of thin, pliable metal, plastic, etc., fitted at one end with a screw cap, and used for holding pastes or semiliquids, which can be squeezed out
4. ☆
   1. electron tube
   2. vacuum tube
5. 1. a tubular tunnel for a railroad, subway, etc.
   2. Brit. an underground electric railway; subway
6. Bot. the lower, united part of a gamopetalous corolla or a gamosepalous calyx
7. Elec. the tubular space bounded by the lines of electric or magnetic force passing through every point on a closed curve on the outside of a charged body
   in full tube of flux or tube of force

Etymology: Fr < L tubus, a pipe

transitive verb tubed, tubing tub′·ing

1. to provide with, place in, or pass through a tube or tubes
2. to make tubular