/ Dictionary / Index D dumortierite: Meaning and Definition of Find definitions for: du•mor•ti•er•ite Pronunciation: (d-môr'tē-u-rīt", dy-), [key] — n. a mineral, aluminum borosilicate. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Dumont d'Urville dump Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language