Perfidy

n.

1.

The act of violating faith or allegiance; violation of a promise or vow, or of trust reposed; faithlessness; treachery. The ambition and perfidy of tyrants. - Macaulay. His perfidy to this sacred engagement. - DeQuincey.

Noun	1.	perfidy - betrayal of a trust Synonyms: perfidiousness, treachery
	2.	perfidy - an act of deliberate betrayal Synonyms: betrayal, treachery, treason

betrayal, deceit, dirty pool, dirty trick, dirty work, disloyalty, double-dealing, duplicity, faithlessness, falseheartedness, falseness, falsity, foul play, hypocrisy, infidelity, insidiousness, perfidiousness, sellout, traitorousness, treacherousness, treachery, treason, unfaithfulness