'Perfidy' definitions:

Definition of 'perfidy'

From: WordNet
noun
Betrayal of a trust [syn: perfidy, perfidiousness, treachery]
noun
An act of deliberate betrayal [syn: treachery, betrayal, treason, perfidy]

Definition of 'Perfidy'

From: GCIDE
  • Perfidy \Per"fi*dy\ (p[~e]r"f[i^]*d[y^]), n.; pl. Perfidies (p[~e]r"f[i^]*d[i^]z). [L. perfidia, fr. L. perfidus faithless; per (cf. Skr. par[=a] away) + fides faith: cf. F. perfidie. See Faith.] The act of violating faith or allegiance; violation of a promise or vow, or of trust reposed; faithlessness; treachery. [1913 Webster]
  • The ambition and perfidy of tyrants. --Macaulay. [1913 Webster]
  • His perfidy to this sacred engagement. --DeQuincey. [1913 Webster]