- Treachery is a betrayal of trust.
An example of treachery is when you cheat on your wife with her best friend.
- betrayal of trust, faith, or allegiance; perfidy, disloyalty, or treason
- an act of perfidy or treason
Origin: Middle English trecherie from Old French tricherie, trickery from trichier, to cheat: see trick
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noun pl. treach·er·ies
- Willful betrayal of fidelity, confidence, or trust; perfidy.
- The act or an instance of such betrayal.
Origin: Middle English trecherie, from Old French, from trichier, to trick, probably from Vulgar Latin *triccāre; see trick.