/ Dictionary / Index I inflationary universe: Meaning and Definition of Find definitions for: infla'tionary u'niverse Pronunciation: [key] — Astron. Astron. a version of the big bang theory in which the universe underwent very rapid growth during the first fraction of a second before it settled down to its current rate of expansion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. inflationary spiral inflationism Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language