/ Dictionary / Index T trioxide: Meaning and Definition of Find definitions for: tri•ox•ide Pronunciation: (trī-ok'sīd, -sid), [key] — n. Chem. an oxide containing three oxygen atoms, as AsO. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: trioxide (Thesaurus) triose trip Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language