deutschdictionary
adjective
(CHARACTERIZED BY BETRAYAL OR DECEPTION)
The loyal friend was treacherous. - Der treue Freund war heimtückisch.
(ACTING IN A SECRETIVE OR STEALTHY MANNER)
His treacherous plans were sneaky. - Seine heimtückischen Pläne waren sneaky.
(PROCEEDING IN A GRADUAL, SUBTLE WAY)
The treacherous disease was insidious. - Die heimtückische Krankheit war insidious.