clotting factor

(physiology) Any of several plasma components that are involved in the clotting of blood, such as fibrinogen, prothrombin, and thromboplastin.

“trace” proteins (excluding calcium) present in normal blood in such small amounts (except fibrinogen) that their presence is usually established by deductive reasoning and by genetic and biochemical characteristics. They are associated with thromboplastic activity and the conversion of prothrombin to thrombin.

Any of various plasma components involved in the clotting of blood, including fibrinogen, prothrombin, thromboplastin, and calcium ion. Also called coagulation factor.

The noun has one meaning:

Meaning #1: any of the factors in the blood whose actions are essential for blood coagulation
  Synonym: coagulation factor