Definition: The word "anticoagulant" is a term used in medical terminology, referring to substances that can help prevent blood clots forming during bleeding. Examples include anticoagulants like warfarin and aspirin for preventing thrombosis (blood clotting), which work by reducing the activity of factor Xa, which initiates the process of bleeding. Anticoagulants also prevent the formation of platelets, another type of blood cell that helps with clotting.