/ Dictionary / Index F FBI: Meaning and Definition of Find definitions for: FBI Pronunciation: [key] — U.S. Govt. U.S. Govt. Federal Bureau of Investigation: the federal agency charged with investigations for the Attorney General and with safeguarding national security. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: fbi (Thesaurus) F.B.A. FBO Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language