conurbation
noun [ C ] formal uk/ˌkɒn.əˈbeɪ.ʃən/ us/ˌkɑː.nɚˈbeɪ.ʃən/
（由多个城镇扩建连接而成的）大都市，集合城市，大都市圈
a city area containing a large number of people, formed by various towns growing and joining together
the conurbations of Tokyo and Osaka 东京和大阪都市圈
Compare: sprawl noun