Treachery

King James Dictionary

Treachery, n. trech'ery. Violation of allegiance or of faith and confidence. The man who betrays his country in any manner, violates his allegiance, and is guilty of treachery. This is treason. The man who violates his faith pledged to his friend, or betrays a trust in which a promise of fidelity is implied, is guilty of treachery. The disclosure of a secret committed to one in confidence, is treachery. This is perfidy.

Webster's Dictionary

(n.) Violation of allegiance or of faith and confidence; treasonable or perfidious conduct; perfidy; treason.