Noun
megaregion (plural megaregions)
A megalopolis.
Yet megaregion criterion have allowed the Great Lakes Megalopolis to maintain status as the most populated region, being home to 53,768,125 people in 2000. Source: Internet
Phoenix is also part of the Arizona Sun Corridor megaregion (MR), which is the 10th most populous of the 11 MRs, and the 8th largest by area. Source: Internet