treason

The betrayal of allegiance toward one's own country, especially by committing hostile acts against it or aiding its enemies in committing such acts.

The betrayal of someone's trust or confidence.

A betraying; treachery; breach of faith.

Specifically—2. Violation by a subject of his allegiance to his sovereign or liege lord, or to the chief authority of the state.

Synonyms See perfidious.