perfidious

Third, Munayyer references Plan Dalet as an example of Zionist perfidiousness, a “military plan for the conquest of Palestine.”

Wherein our men are guilty of the most horrid cowardice and perfidiousness, as he says and tells it, that ever Englishmen were.

A more striking example of perfidiousness was effectually to stir Voltaire's resentment a little later.

I had not been married eight months, when you suspected me of every perfidiousness, and you even told me so.