the hypothetical set of multiple possible universes (including the historical universe we consistently experience) that together comprise everything that exists and can exist: the entirety of space, time, matter and energy as well as the physical laws and constants that describe them. An infinite realm of being or potential being of which the universe is regarded as a part or instance.

Etymology: based on universe, from Latin multi, combining form of multus, ”much, many” + verse, from versus, "turned".

[Henryk Waniek]