/ Dictionary / Index F F.D.: Meaning and Definition of Find definitions for: F.D. Pronunciation: [key] Fidei Defensor. fire department. focal distance. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. fcy. FDA Related Content Daily Word Quiz: winsome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language