In a broader sense, it refers to the city or state of origin of a colony (as of ancient Greece), a city regarded as a center of a specified activity, or a large important city.

Antiquity

In the past, metropolis was the designation for a city or state of origin of a colony. Many large cities founded by ancient civilizations have been considered important world metropolises of their times due to their large populations and importance. Examples include Alexandria, Angkor, Antioch, Athens, Babylon, Beirut, Benares, Byblos, Cahokia, Carthage, Constantinople, Corinth, Damascus, Dholavira, Ephesus, Great Zimbabwe, Harappa, Jerusalem, Leptis Magna, Nanjing, Nineveh, Macchu Picchu, Mohenjo-Daro, Rome, Sarai, Side, Siracuse, Tenochtitlan, Teotihuacan, Tikal, Tyre, Xian and Ur. Some of these ancient metropolises survived until the modern days and are among the world's oldest continuously inhabited cities.

Etymology and modern usage

The word comes from the Greek metropolis ("mother city"), 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.

In modern usage the word is also used for a metropolitan area, a set of adjacent and interconnected cities clustered around a major urban center. In this sense "metropolitan" usually means "spanning the whole metropolis" (as in "metropolitan administration"); or "proper of a metropolis" (as in "metropolitan life", and opposed to "provincial" or "rural").

Global/world city

The concept of a Global city (or a World city) means a city that has a direct and tangible effect on global affairs through socioeconomic means. The term has become increasingly familiar, because of the rise of globalization (i.e., global finance, communications, and travel). An attempt to define and categorize world cities by financial criteria was made by the Globalization and World Cities Study Group & Network (GaWC), based primarily at Loughborough University in England. The study ranked cities based on their provision of "advanced producer services" such as accountancy, advertising, finance and law. The Inventory identifies three levels of world cities and several sub-ranks (See World cities ranking).

A metropolis isn't necessarily a global city, or being one, it could not be among the top ranking due to its standards of living, development, and infrastructures.

Canada

Statistics Canada defines a census metropolitan area as one or more adjacent municipalities situated around a major urban core where the urban core has a population of at least 100,000.