Multiverse vs. Omniverse — What's the Difference?

The multiverse is a hypothetical group of multiple universes. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them.

(scifi) The entire set of co-existing universes, multiverses, etc.

The collection of parallel universes that comprise all of reality in some quantum mechanical and cosmological theories.

A similar collection of parallel universes in a work of fiction or a series of related works of fiction.

(philosophy) The world, considered as lacking in purpose, design, or predictability.

The hypothetical group of all the possible universes in existence.

(fiction) The different canons, continuities or timelines of a fictional property, considered as a whole.