Metro (n.)

Paris underground, 1904, from French abbreviation of Chemin de Fer Métropolitain "Metropolitan Railway" (see metropolitan (adj.)). French chemin de fer "railroad" is literally "iron road." Construction began in 1898.

Others are reading

Definitions of Metro from WordNet

metro (n.)
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'
Synonyms: tube / underground / subway system / subway