perfidy

perfidy n

Fr. < L. perfid-us < per-, away entirely, to destruction + fid-ēs, faith.

1. Treachery; deceit; betrayal; falseness; disloyalty; deception; duplicity; pretense; feigning.
2. Violation of trust; breach of promise.
3. Doubt; lack of trust; loss of faith.
4. Mirage; illusion.