Main Entry: vitamin K

Function: noun

Etymology: from the initial letter of Dan & Swedish koagulation coagulation, Norwegian koagulasjon & German Koagulation

Date: circa 1935

1 : either of two naturally occurring fat-soluble vitamins C₃₁H₄₆O₂ and C₄₁H₅₆O₂ essential for the clotting of blood because of their role in the production of prothrombin —called also vitamin K₁, vitamin K₂
2 : any of several synthetic compounds closely related chemically to natural vitamins K₁ and K₂ and of similar biological activity