Definition of "multiverse"

Visible nature is all plasticity and indifference, a multiverse, as one might call it, and not a universe.

1895 October, William James, “Is Life Worth Living?”, in International Journal of Ethics‎, page 10

I've never gone through a place like Racine without thinking which house with the rubber-tire swing for kids and piano-practicing inside was like Stiva Lausch's, who had two daughters brought up with every refinement, including piano lessons, and how such little-speaking Odessa-bred sons had gotten on a track like this through the multiverse.

1953, Saul Bellow, chapter 6, in The Adventures of Augie March, New York: Viking Press, pages 94–95

And, it must be remembered, that in the great multiverse they were a mere scattering of seeds; seeds that must survive many elements if they were to grow.

1963 May, Michael Moorcock, “The Blood Red Game”, in Science Fiction Adventures, volume 6, number 32, London: Nova Publications

I have been describing show us that the multiverse exists and that it contains many counterparts of each particle in the tangible universe. To reach the further conclusion that the multiverse is roughly partitioned into parallel universes, we must consider interference phenomena involving more than one tangible particle.

1998 , David Deutsch, The Fabric of Reality, New York: Penguin Books, page 46

I can’t help feeling that in the closest arm of the multiverse, there is a version of me that is fatter and happier.

2020, Raven Leilani, Luster, Picador, published 2021, page 26