>>11626847At one point astronomers thought that the Milky Way was the entire Universe before Hubble definitively proved that Andromeda was a separate galaxy. Early theories on multiple galaxies referred to other galaxies as "island Universes."
So, there isn't any reason why other Universes couldn't be called other Universes. I imagine their proper names would be like most astronomical objects, a catalog or instrument identifier followed by a number.
