'metro' definitions:

Definition of 'metro'

From: WordNet
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'" [syn: metro, tube, underground, subway system, subway]

Definition of 'metro'

From: GCIDE
  • Subway \Sub"way`\, n.
  • 1. An underground way or gallery; especially, a passage under a street, in which water mains, gas mains, telegraph wires, etc., are conducted. [1913 Webster]
  • 2. An underground railroad, usually having trains powered by electricity provided by an electric line running through the underground tunnel. It is usually confined to the center portion of cities; -- called also tube, and in Britain, underground. In certain other countries (as in France or Russia) it is called the metro. [PJC]

Synonyms of 'metro'

From: Moby Thesaurus