noun, plural meg·a·cit·ies.
Examples from the Web for megacity
Nearly two-thirds of the sewage in the megacity of Dhaka, with 15 million people, is untreated.
A growing array of critics understand the need to break with the megacity mantra.
“The megacity of the poor,” is how the urban geographer Nazrul Islam describes his hometown.
The damage done to people by megacity urbanism is most pronounced in poorer countries.City Leaders Are in Love With Density but Most City Dwellers Disagree|Joel Kotkin|September 16, 2013|DAILY BEAST