A metropolis is a large city or urban area 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 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. Big cities belonging to a larger urban agglomeration, but which are not the core of that agglomeration, are not generally considered a metropolis but a part of it. The plural of the word is most commonly metropolises. For urban centers outside metropolitan areas that generate a similar attraction at smaller scale for their region, the concept of the Regiopolis, short regio, was introduced by German professors in 2006.