Per*fid"i*ous (pẽr*fĭd"ĭ*ŭs;
277), a. [L. perfidious.] 1.
Guilty of perfidy; violating good faith or vows; false to trust
or confidence reposed; teacherous; faithless; as, a perfidious
friend. Shak.
2. Involving, or characterized by,
perfidy. "Involved in this perfidious fraud."
Milton.