/ Dictionary / Index O oxonium compound: Meaning and Definition of Find definitions for: ox•o'ni•um com"pound Pronunciation: (ok-sō'nē-um), [key] — Chem. Chem. a salt formed by the reaction of an acid with an organic compound containing a basic oxygen atom. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Oxonian oxonium ion Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language