supercity

[ soo-per-sit-ee ]
/ ˈsu pərˌsɪt i /

noun, plural su·per·cit·ies.

a large, heavily populated urban area that includes several cities; megalopolis.
a very large city.

Origin of supercity

An Americanism dating back to 1920–25; super- + city
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019