treacherous

1 ENTRIES FOUND:
treacherous /ˈtrɛtʃərəs/ adjective
treacherous
/ˈtrɛtʃərəs/
adjective
Britannica Dictionary definition of TREACHEROUS
[more treacherous; most treacherous]
1 
: not able to be trusted : showing that someone cannot be trusted
2 
: very dangerous and difficult to deal with

— treacherously

adverb