tube 
(tb, tyb)
(tb, tyb)n.
1.
a. A hollow cylinder, especially one that conveys a fluid or functions as a passage.
b. An organic structure having the shape or function of a tube; a duct: a bronchial tube.
2. A small flexible cylindrical container sealed at one end and having a screw cap at the other, for pigments, toothpaste, or other pastelike substances.
3. Music The cylindrical part of a wind instrument.
4. Electronics
a. An electron tube.
b. A vacuum tube.
5. Botany The lower, cylindrical part of a gamopetalous corolla or a gamosepalous calyx.
6.
a. A tunnel.
b. An underground railroad system, especially the one in London, England.
7. The elongated space inside a wave when it is breaking.
8.
a. An inner tube.
b. An inflatable tube or cushion made of rubber or plastic and used for recreational riding, as behind a motor boat or down a snow-covered slope.
9. Informal
a. Television: What's on the tube?
b. A television set.
10. tubes Informal The fallopian tubes.
v. tubed, tub·ing, tubes
v.tr.
1. To provide with a tube; insert a tube in.
2. To place in or enclose in a tube.
v.intr.
Idiom: To ride or float on an inflated tube for recreation.
down the tubes/tube Slang
Into a state of failure or ruin: saw her plans go down the tubes.
[French, from Old French, from Latin tubus.]