perfidious

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

And it must be practice first, that must make words credible, when the person by perfidiousness hath forfeited his credit.

Saith Q. Curtius, Perfidiousness is a crime which no merits can mitigate.

Sabine's eyes opened upon new vistas of man's perfidiousness.