1) An act of deliberate betrayal 2) Betrayal 3) Betrayal of a trust 4) Breach of faith 5) Disloyalty 6) French word used in English 7) Perfidiousness 8) Treacherousness 9) Treachery 10) Type of War crime 1) Betrayal 2) Deceit 3) Disloyalty 4) Perfidiousness 5) Sellout 6) Treachery 7) Treason 
In the context of war, perfidy is a form of deception in which one side promises to act in good faith (e.g., by raising a flag of surrender) with the intention of breaking that promise once the enemy has exposed themselves (e.g., by coming out of cover to capture the `surrendering` enemy). Perfidy constitutes a breach of the laws of war and ther.....
• (n.) The act of violating faith or allegiance; violation of a promise or vow, or of trust reposed; faithlessness; treachery.
Per'fi·dy (pẽr'fĭ*dȳ) noun ; plural Perfidies (- dĭz). [ Latin perfidia , from Latin perfidus faithless; per (cf. Sanskrit parā away) + fides faith: confer French perfidie . See Faith .] The act of vi...
treachery breaking of faith 
[n] - betrayal of a trust
perfidy 1. The deceitful violation of faith or promise; base breach of faith or betrayal of the trust reposed in someone; treachery. 2. Often, the profession of faith or friendship in order to deceive or to betray. 3. The quality or state of being faithless or disloyal; treachery. 4. An act or an instance of disloyalty.
perfidiousness noun betrayal of a trust
an act of deliberate betrayal[Difficult words] an act of deliberate betrayal[Obscure words] an act of deliberate betrayal