metr-

WordReference Random House Unabridged Dictionary of American English © 2025

metr-, 

1. var. of metro- ² before a vowel:
   metralgia.

WordReference Random House Learner's Dictionary of American English © 2025

met•ro¹ /ˈmɛtroʊ/   n., pl. -ros. [often: Metro]

1. Transport the underground railway of certain cities, as Washington, D.C., and Paris, France:
   [countable] Compare the metros in both cities.
   [uncountable] You can get there by metro.

WordReference Random House Unabridged Dictionary of American English © 2025

met•ro¹  (me′trō), n., pl. -ros. (often cap.)

1. Transport the underground electric railway of Paris, France, Montreal, Canada, Washington, D.C., and other cities.
2. Transport subway (def. 1).

• French métro, short for chemin de fer métropolitain metropolitan railroad
• 1900–05

met•ro²  (me′trō), adj., n., pl. -ros. [Informal.]
adj. 

1. Informal Terms metropolitan (defs. 1, 2).

n. 

2. Informal Terms metropolis (defs. 1, 2).
3. Informal Terms, British Terms (often cap.) [Chiefly Canadian.] the government or jurisdiction of a large city.

• 1900–05; by shortening; or independent use of metro-³

metro-¹ ,

1. a combining form meaning "measure,'' used in the formation of compound words:
   metronome.

• combining form representing Greek métron measure

metro-² ,

1. a combining form meaning "uterus,'' used in the formation of compound words:
   metrorrhagia.

Also,[esp. before a vowel,] metr-. 

• combining form representing Greek mé̄tra womb

metro-³ :

1. a combining form representing metropolis or metropolitan in compound words:
   metroflight;
   metroland;
   Metroliner.