adjective Date: 14th century characterized by or manifesting treachery ; perfidious , 2. likely to betray trust ; unreliable , providing insecure footing or support , marked by hidden dangers, hazards, or perils, see: faithless ~ly adverb ~ness noun
TREACHEROUS
Meaning of TREACHEROUS in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012