This is not the Stephen King Macroverse
Base Case - Macro-Universe
The name is usually applied to a very large universe that is much larger than what is normal for such a structure.
There is a strong possibility that most normal universes are already infinite in size. Being even larger, that just means that these macro-universes just have sizes that are larger than infinity itself, usually being some type of higher order infinity or trans-infinity.
The interior of a macroverse is indescribable. It appears to be made of repeating fractal structures composed of stars, galaxies, and even entire superclusters. These objects swirl around each other in vortexes trillions or quadrillions of light years wide, which in turn combine to form huge pillars and sheets of vortexes. The pillars and sheets stack on top of each other and swirl around in larger and larger groups in much the same way that turtlies do; four-, five-, and six dimensional polytopes, impossible Escher-like bridges between spheres of light, and objects so vast that even deities could not comprehend their true size.
The most advanced of civilizations, which have practically ascended to godhood or even past this, use macroverses for large-scale storage of immense battle fleets, fortresses, or other tech that simply needs a place to stay before it is deployed.
Some macroverses are dead universes that have accelerated in expansion so much that they have turned into ludicrously massive bubbles of nothingness, making them extremely efficient for storage.
Despite the fact that it is usually used to refer to very lard universes, the name Macroverse, as stated before, can apply to any type of verse.
A Macro-Multiverse for example, would be a Multiverse with a much higher number of universes than what is normal, possibly uncountable infinite universes or trans-infinite universes. Probably forming larger and larger structures of universes inside them. It probably will also have some macro-universes inside it, but not necessarily.
The same applies to any other type of verse.
These structures usually exist at a much higher level in the cosmological hierarchy than what would be otherwise normal for their type. A macro-universe could exist at the level of a multiverse or even higher, probably up to the omniverse level.