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1. The collection of parallel universes that comprise all of reality in some quantum mechanical and cosmological theories.
2. A similar collection of parallel universes in a work of fiction or a series of related works of fiction.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Astronomy) astronomy the aggregate of all existing matter, of which the universe is but a tiny fragment
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014