n. 不诚实, 背信弃义(行为)

[法] 叛变, 出卖, 背信弃义

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.

The ambition and perfidy of tyrants. --Macaulay.

His perfidy to this sacred engagement. --DeQuincey.