Pĕr'fi-dy, n.

n. [Fr. perfidie, It., Sp., & Lat. perfidia, from Lat. perfidus, faithless, from the prefix per, through, beyond, and fidus, faithful; It. & Sp. perfido, Fr. perfide.] The act of violating faith, a promise, vow, or allegiance; faithlessness; treachery; the violation of a trust reposed. “Such was his perfidy to this sacred engagement.” De Quincey.