A metropolis (/mɪˈtrɒpəlɪs, -plɪs/) is a large city or conurbation which is a significant economic, political, and cultural center for a country or region, and an important hub for regional or international connections, commerce, and communications. The term is Greek (Greek: μητρόπολη) and means the "mother city" of a colony (in the ancient sense), that is, the city which sent out settlers. This was later generalized to a city regarded as a center of a specified activity, or any large, important city in a nation.
A big city belonging to a larger urban agglomeration, but which is not the core of that agglomeration, is not generally considered a metropolis but a part of it. The plural of the word is metropolises, although the Latin plural is "metropoles", from the Greek "metropoleis" (Greek: μητρoπόλεις).
For urban centers outside metropolitan areas that generate a similar attraction at smaller scale for their region, the concept of the regiopolis ("regio" for short) was introduced by German academics in 2006.
In the ancient world, a metropolis was the city or state of origin of a colony.
Metropolis is a Greek word, coming from μήτηρ, mḗtēr meaning "mother" and πόλις, pólis meaning "city" or "town", which is how the Greek colonies of antiquity referred to their original cities, with whom they retained cultic and political-cultural connections. The word was used in post-classical Latin for the chief city of a province, the seat of the government and, in particular, ecclesiastically for the seat or see of a metropolitan bishop to whom suffragan bishops were responsible. This usage equates the province with the diocese or episcopal see.