A confutation is the act of refuting someone's point forcefully. Accused criminals must offer confutation if they hope to be found innocent.
If you know the verb confute — which means to overwhelm through an argument — this noun will be a no-brainer: it refers to the act of confuting, or a statement that confutes. The meaning is not that far removed from refutation, with which confutation shares a Latin root. A confutation proves that another idea is false or nonsensical. People who argue for a living, like lawyers, are masters of confutation.