/ Dictionary / Index R rarefaction: Meaning and Definition of Find definitions for: rar•e•fac•tion Pronunciation: (râr"u-fak'shun), [key] — n. the act or process of rarefying. the state of being rarefied. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rarefaction (Thesaurus) raree show rarefied Related Content Daily Word Quiz: cur Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language