treachery treacherousness • treacle · · · Info · Definitions · Synonyms · Characters · · treachery · · Text Latin · · Script 9 · · Length Definitions · · · (noun) betrayal of a trust. Synonyms: perfidy, perfidiousness. · · Noun Definition 1 (noun) an act of deliberate betrayal. Synonyms: betrayal, treason, perfidy. · · Noun Definition 2 Synonyms · · · perfidy · · Synonym 1 perfidiousness · · Synonym 2 betrayal · · Synonym 3 treason · · Synonym 4 Characters · · a latin small letter a U+0061 c latin small letter c U+0063 e latin small letter e U+0065 h latin small letter h U+0068 r latin small letter r U+0072 t latin small letter t U+0074 y latin small letter y U+0079