/ Dictionary / Index F 4-F: Meaning and Definition of Find definitions for: 4-F Pronunciation: (fôr'ef', fōr'-), [key] — n. a U.S. Selective Service classification designating a person considered physically, psychologically, or morally unfit for military duty. a person so classified. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. four-eyes four flush Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language