/ Dictionary / Index M metamorphism: Meaning and Definition of Find definitions for: met•a•mor•phism Pronunciation: (met"u-môr'fiz-um), [key] — n. a change in the structure or constitution of a rock due to natural agencies, as pressure and heat, esp. when the rock becomes harder and more completely crystalline. metamorphosis. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: metamorphism (Thesaurus) metamorphic facies metamorphose Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language