treacherously

adverb
1
in a way that involves hurting somebody who trusts you
خیانت‌آمیز, به‌طور خیانت‌آمیز, خائنانه
2
in a dangerous way, especially when something seems safer than it is
خطرناکانه, به صورت خائنانه, خیانت‌آمیز, موذیانه
treacherously icy conditions on the roads