D defs.my
Entry 2 senses Webster, 1913

Perfidious

/(pẽr*fĭd"ĭ*ŭs; 277)/ · Per·fid·i·ous · IPA /pɚˈfɪdi.əs/
01 a. Guilty of perfidy; violating good faith or vows; false to trust or confidence reposed; treacherous; faithless; as, a perfidious friend.
  1. 1.
    Guilty of perfidy; violating good faith or vows; false to trust or confidence reposed; treacherous; faithless; as, a perfidious friend.
  2. 2.
    Involving, or characterized by, perfidy.