/throm'beuh plas"tin/ , n.
1. Biochem. a lipoprotein in the blood that converts prothrombin to thrombin.
2. Pharm. a commercial form of this substance, obtained from the brains of cattle, used chiefly as a local hemostatic and as a laboratory reagent in blood prothrombin tests. Also called thrombokinase /throm'boh kuy"nays, -kin"ays/ .
[ 1910-15; THROMBO- + -PLAST + -IN 2 ]