perfidy

per·fi·dy  (pûrf-d)

n. pl. per·fi·dies

1. Deliberate breach of faith; calculated violation of trust; treachery: "the fink, whose perfidy was equaled only by his gall" (Gilbert Millstein).

2. The act or an instance of treachery.

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[Latin perfidia, from perfidus, treacherous : per-, to destruction; see per- + fids, faith; see bheidh- in Indo-European roots.]

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perfidy

1. breach of trust, especially treachery or treason.
2. an act or instance of this. — perfidious, adj.

See also: Treason

Thesaurus

Noun	1.	perfidy - betrayal of a trust                   perfidiousness, treachery disloyalty - the quality of being disloyal insidiousness - the quality of being designed to entrap
	2.	perfidy - an act of deliberate betrayal         betrayal, treachery, treason knavery, dishonesty - lack of honesty; acts of lying or cheating or stealing double cross, double-crossing - an act of betrayal; "he gave us the old double cross"; "I could no longer tolerate his impudent double-crossing" sellout - an act of betrayal