fbi fb • fbi agent · · · Info · Definitions · Characters · · fbi · · Text Latin · · Script 3 · · Length 1 · · Syllables Definitions · · · (noun) a federal law enforcement agency that is the principal investigative arm of the Department of Justice. Synonyms: Federal Bureau of Investigation, FBI. · · Noun Definition 1 Characters · · b latin small letter b U+0062 f latin small letter f U+0066 i latin small letter i U+0069