Breadcrumb Home > Dictionary > Index A alumina: Meaning and Definition of Find definitions for: a•lu•mi•na Pronunciation: (u-l'mu-nu), [key] — n. the natural or synthetic oxide of aluminum, AlO, occurring in nature in a pure crystal form as corundum. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: alumina (Thesaurus) alumin- alumina cement ✖ Related Content Daily Word Quiz: derogate Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language