noun
megalopolis
meg-uh-LAH-puh-lis/ˌmeɡəˈlɑːpəlɪs/
A very large, densely populated urban region.
Three dense city centers and their surrounding development form one megalopolis.

Etymology
The Greek pieces mean “great city,” and the compound was used as an epithet for great cities in antiquity. Its modern sense emphasizes a vast, heavily populated urban complex.
In context
a megalopolis is a cluster of nearby metropolitan areas for example the northeast megalopolis is an area on the eastern seaboard of the united states that goes from boston down to washington
More examples
- Millions of people travel across the megalopolis each day.
- The coastal megalopolis stretches across several state lines.
- Providing affordable housing is a challenge in many megalopolises.
Forms
megalopolis · megalopolises · megalopoleis
Similar words
- metropolis
- Usually names one major city rather than an entire urban region.
- conurbation
- Emphasizes neighboring cities merging into one continuously built-up area.