perfidious- word of the day

per·fi·dy [ púrfidee ]
noun

Definition:
deliberate treachery: treachery or deceit ( formal )

[Late 16th century. < Latin perfidia < perfidus "treacherous" < per fidem decipere "deceive through trustingness" < fides "faith, trust"]

per·fid·i·ous [ pər fíddee əss ] adjective