tube

Noun

• 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'
    

• (anatomy) any hollow cylindrical body structure

• a hollow cylindrical shape

• electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

• conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases

Verb

• place or enclose in a tube

• ride or float on an inflated tube
  • We tubed down the river on a hot summer day
    

• convey in a tube
  • inside Paris, they used to tube mail
    

• provide with a tube or insert a tube into

Related words

• Synonyms: 
  metro , underground , subway system , subway , tube-shaped structure , pipe , vacuum tube , thermionic vacuum tube , thermionic tube , electron tube , thermionic valve , tubing