megalopolis is incorrectly written, and should be written as "megalopolis" being its meaning:
Term of Greek origin, from megas mega megale: large and poleos polis: City: big city. The word was introduced by the French geographer Jean Gottmann in 1961 to designate conurbations of 10 million or more inhabitants. A conurbation is the result of the rapid growth of a great city like Madrid that ends up swallowing nearby towns like Móstoles, Vallecas, Vicálvaro, Coslada, etc; or also the growth fast or slow two major cities or more arriving to join urban.