Read the dictionary definition of TUBE. All definitions for this word.
1. an electric railway operating below the surface of the ground (usually in a city)
1. in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'
2. conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases
3. electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope
4. (anatomy) any hollow cylindrical body structure
5. a hollow cylindrical shape
6. place or enclose in a tube
7. ride or float on an inflated tube
1. We tubed down the river on a hot summer day
8. convey in a tube
1. inside Paris, they used to tube mail
9. provide with a tube or insert a tube into