Merriam-Webster Collegiate Dictionary - metropolis

 noun  Etymology: Middle English, from Late Latin, from Greek metropolis, from metr-, meter mother + polis city — more at mother, police  Date: 14th century  1. the chief or capital city of a country, state, or region  2. the city or state of origin of a colony (as of ancient Greece)  3.  a. a city regarded as a center of a specified activity a great business ~  b. a large important city the world's great ~es — P. E. James