A super metropolitan region that extends as a union of conurbations is typically referred to as a "Megalopolis" or a "Megalopolitan area."
This term is used to describe a vast, continuous urban area that results from the merging of several adjacent metropolitan areas or conurbations.
Megalopolises are characterized by their high population density, extensive urban sprawl, and interconnectedness.
One of the most famous examples of a megalopolis is the Northeast Megalopolis in the United States, which includes cities like Boston, New York City, Philadelphia, and Washington, D.C.