/ Dictionary / Index O ONF: Meaning and Definition of Find definitions for: ONF Pronunciation: [key] Old North French. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. one-worlder ONFr. Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language