Meaning of expanding universe

expand'ing u'niverse

Pronunciation: [key]
— Astron. Astron.
  1. a representation of the universe, based on the observed redshifts of distant galaxies, in which the galaxies are assumed to be receding from each other at a speed proportional to their separation as a result of the expansion of the universe. Cf. Hubble's constant, cosmological redshift.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.