Apeira (other names: Iraee, Final Realm) is the ultimate tier in Lord Aspect's cosmology. It is not infinite, since nothing (excluding the power of God) is infinite for Lord Aspect. This is final tier of anything.All the voids, All the space, All the time etc. Nothing can surpass it. If you will imagine anything that is beyond Apeira, it's still inside it.
Innards of it is anything that exists. Apeira is made up out of ultimately unimaginable amount of dimensions.
Every single realm, located within it, is classified as a Dimension.
Low tier dimensions, are lowest realms to be contained by Apeira. They can't contain anything. 0D ones.
Med tier dimensions are a bit bigger fractions of Apeira. 1D-7D ones.
High tier dimensions are immeasurable sets of matter and time. Largest dimensions. 8D-10D ones.
Top Tier, and beyond it
All the dimensions, that entities below God can't surpass. 11D ones.