His act of treachery was seen as a betrayal by his friends.
She was known for her deceitful ways, always plotting treachery behind people's backs.
The king saw the rebellion as a treasonous act of treachery against the crown.
He felt betrayed and double-crossed when he found out about the treachery of his business partner.
The workplace was full of backstabbing and treachery, with colleagues constantly trying to undermine each other.