A more thorough explanation:

A megalopolis is a large, densely populated urban area that is made up of several cities and towns that have grown together. It is like one giant city that stretches for miles and miles.

For example, the Northeast Megalopolis in the United States is made up of cities like Boston, New York City, Philadelphia, and Washington D.C. These cities are all close together and have grown so much that they almost blend into one another.

Another example is the Pearl River Delta Megalopolis in China, which includes cities like Hong Kong, Shenzhen, and Guangzhou. These cities have grown so much that they are now connected by bridges and tunnels.

These examples illustrate the definition of megalopolis because they show how several cities and towns have grown together to form one large urban area. The population in these areas is very high, and there are many buildings, roads, and other infrastructure to support the large number of people who live and work there.