City size refers to the population or physical extent (area) occupied by a city. It is often measured by the number of residents living within its boundaries or by the land area it covers.
Related terms
Megacity: A very large metropolitan area with a population over 10 million inhabitants.
Urban sprawl: The unplanned expansion of urban areas into surrounding suburban or rural areas.
Population density: The average number of people per square kilometer (or square mile) in an area.