anticoagulant

A substance that prevents coagulation (stops blood from clotting); especially, any of a group of pharmaceutical drugs that reduce the clotting speed or affinity of the blood by any of several mechanisms (e.g., inhibiting platelet function, inhibiting clotting factor (protein) production or function, increasing antithrombin function).

抗凝剂

That prevents coagulation, that stops blood from clotting.