/ Dictionary / Index R rarefy: Meaning and Definition of Find definitions for: rar•e•fy Pronunciation: (râr'u-fī"), [key] — v., -fied, -fy•ing. —v.t. to make rare or rarer; make less dense: to rarefy a gas. to make more refined, spiritual, or exalted. —v.i. to become rare or less dense; become thinned: Moisture rarefies when heated. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rarefy (Thesaurus) rarefied rarely 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