tube in WordNet English dictionary

1. electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope
   tube  vacuum tube  thermionic vacuum tube  thermionic tube  electron tube  thermionic valve 
   
2. an electric railway operating below the surface of the ground (usually in a city)
   "in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'"
   metro  tube  underground  subway system  subway 
   
3. a hollow cylindrical shape
   pipe  tube 
   
4. conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases
   tube  tubing 
   
5. (anatomy) any hollow cylindrical body structure
   tube  tube-shaped structure 
   

1. place or enclose in a tube
   tube 
   
2. convey in a tube
   "inside Paris, they used to tube mail"
   tube 
   
3. ride or float on an inflated tube
   "We tubed down the river on a hot summer day"
   tube 
   
4. provide with a tube or insert a tube into
   tube