treacherous
— Adjective
– English
~ dangerously unstable and unpredictable; "treacherous winding roads"; "an unreliable trestle"
treacherous
— Adjective
– English
~ tending to betray; especially having a treacherous character as attributed to the Carthaginians by the Romans; "Punic faith"; "the perfidious Judas"; "the fiercest and most treacherous of foes"; "treacherous intrigues"
treacherously
— Adverb
– English
~ in a disloyal and faithless manner; "he behaved treacherously"; "his wife played him false"