Decimation was a form of military discipline used by the Roman army, where one in every ten soldiers in a unit was executed as punishment for the entire group’s cowardice or failure. This brutal practice aimed to instill fear and ensure loyalty among troops. The term derives from the Latin word "decimus," meaning "tenth," reflecting the method of selecting those to be punished. Although it was intended to maintain discipline, decimation often led to significant losses in manpower and morale.