/ Dictionary / Index I IFF: Meaning and Definition of Find definitions for: IFF Pronunciation: [key] — Mil. Mil. Identification, Friend or Foe: a system of transmitters and transponders that uses coded signals to distinguish between friendly and hostile aircraft. iff Pronunciation: [key] — Math. Math. if and only if. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Ife iffen Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language