Treachery (noun)

Violation of allegiance, of trust, or of a faith pledged; treachery; breach of faith; betrayal.

Origin:

From old french traîtrise, from latin traditio, tradere ("to betray").

Examples:

1. The treachery of the spy was discovered before he could do any harm.
2. He was executed for treachery against his country.
3. The treachery of the traitor was a shock to the whole nation.
4. Treachery is the worst thing that can happen in a friendship.
5. The treachery of Judas is one of the most famous betrayals in history.