fifth columnist fifth column • fifty-acre · · · Info · Definitions · Synonyms · Characters · · fifth columnist · · Text Common · · Latin · · Scripts 15 · · Length Definitions · · · (noun) a member of a clandestine subversive organization who tries to help a potential invader. Synonyms: saboteur. · · Noun Definition 1 Synonyms · · · one-fifth · · Synonym 1 fifth · · Synonym 2 fifth part · · Synonym 3 twenty percent · · Synonym 4 5th · · Synonym 5 Characters · · space U+0020 c latin small letter c U+0063 f latin small letter f U+0066 h latin small letter h U+0068 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F s latin small letter s U+0073 t latin small letter t U+0074 u latin small letter u U+0075