Perfidy (noun)

1. Deliberate breach of faith or trust.
2. Treachery; betrayal.

Origin:

From the latin word perfidia, from per- "completely" + fides "faith".

Examples:

1. The perfidy of the traitor was discovered and he was punished.
2. He felt that the perfidy of his friend was unforgivable.
3. The perfidy of the country's leaders was exposed to the public.
4. The perfidy of the company was the reason for its downfall.
5. He committed perfidy by betraying his comrades.