What is the exact English word for the meaning paara its a Malayalam word often referred to as backbiting or similar terms?

Backbiting is essentially talking behind someone's back. Paara in Malayalam by definition woud be sth done or said against someone when he is not expecting it, generally without his knowledge too (i.e behind his back). Thus, it is unexpected deception. In English, hoodwink means "to deceive" and double-cross means "to deceive someone who believes that you are cooperating". Paara could be translated, though partially, as double-cross.