/ Dictionary / Index I ionone: Meaning and Definition of Find definitions for: i•o•none Pronunciation: (ī'u-nōn"), [key] — n. Chem. a light-yellow to colorless, slightly water-soluble liquid that is either one or a mixture of two unsaturated ketones having the formula CHO, used chiefly in perfumery. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ionomer ionopause Related Content Daily Word Quiz: reiterate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language