/ Dictionary / Index O -oon: Meaning and Definition of Find definitions for: -oon Pronunciation: [key] a suffix occurring in words borrowed from French and other Romance languages (bassoon; balloon; dragoon; pontoon), and on this model occasionally used in the formation of new nouns in English (spittoon). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. oomycota Oona Related Content Daily Word Quiz: apogee Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language