say it: MEH-troh
metro is a noun meaning "an electric railway operating below the surface of the ground (usually in a city)". It carries one recorded sense.
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'”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for metro come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.