Which term is commonly defined as a vast urban region with a population greater than ten million?

The term that is commonly defined as a vast urban region with a population greater than ten million is "Megalopolis." This concept refers to a large, densely populated urban area that encompasses multiple cities and their surrounding suburbs, creating a continuous network of urban development. Megalopolises typically exhibit significant economic, cultural, and social interactions facilitated by their size and the sheer number of people living in close proximity.

In urban planning and development, the definition of a megalopolis is particularly important, as it often highlights the challenges and opportunities associated with managing such large-scale urban areas, including transportation, infrastructure, environmental concerns, and urban sprawl. Understanding this term helps planners design and implement policies that support sustainable growth and livability in these expansive regions.

In contrast, other terms like conurbation generally refer to an area where two or more cities have merged, but this does not specifically denote the population threshold of ten million. A floating city is a novel concept related to urban development on water, while Intramuros is a historic walled city in Manila, Philippines, and does not relate to the definition of large metropolitan areas.