/ Dictionary / Index - -onic: Meaning and Definition of Find definitions for: -onic Pronunciation: [key] a suffix used in forming names of acids, esp. carboxylic acids obtained by oxidation of aldoses: gluconic acid. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ONI oniomania Related Content Daily Word Quiz: labyrinth Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language