| Noun | 1. | clotting factor - any of the factors in the blood whose actions are essential for blood coagulation plasma protein - any of the proteins in blood plasma factor I, fibrinogen - a protein present in blood plasma; converts to fibrin when blood clots factor II, prothrombin - a protein in blood plasma that is the inactive precursor of thrombin factor III, thrombokinase, thromboplastin - an enzyme liberated from blood platelets that converts prothrombin into thrombin as blood starts to clot calcium ion, factor IV - ion of calcium; a factor in the clotting of blood cothromboplastin, factor VII, proconvertin, stable factor - a coagulation factor formed in the kidney under the influence of vitamin K antihaemophilic factor, antihaemophilic globulin, antihemophilic factor, antihemophilic globulin, factor VIII, Hemofil - a coagulation factor (trade name Hemofil) whose absence is associated with hemophilia A Christmas factor, factor IX - coagulation factor whose absence is associated with hemophilia B factor X, prothrombinase - coagulation factor that is converted to an enzyme that converts prothrombin to thrombin in a reaction that depends on calcium ions and other coagulation factors factor XI, plasma thromboplastin antecedent - coagulation factor whose deficiency results in a hemorrhagic tendency factor XII, Hageman factor - coagulation factor whose deficiency results in prolongation of clotting time of venous blood factor XIII, fibrinase - in the clotting of blood thrombin catalyzes factor XIII into its active form (fibrinase) which causes fibrin to form a stable clot |