warfarin UK /ˈwɔː.fə.ɹɪn/US /ˈwɔɹ.fəɹ.ɪn/ noun3 •A coumarin salt, warfarin sodium, found in certain clovers, that retards blood coagulation •Manufactured as a pharmaceutical drug and used in low dosage, with regular monitoring, for the prevention of thrombosis and embolism. •Manufactured as a chemical, used in high dosage as a pesticide. formswarfarins