Breadcrumb Home > Dictionary > Index T thoria: Meaning and Definition of Find definitions for: tho•ri•a Pronunciation: (thôr'ē-u, thōr'-), [key] — n. Chem. a white, heavy, water-insoluble powder, ThO, used chiefly in incandescent mantles, as the Welsbach gas mantle. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Thorez thorianite ✖ Related Content Daily Word Quiz: temporize Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language