vitamin k

from WordNet (r) 3.0 (2006)

vitamin K
    n 1: a fat-soluble vitamin that helps in the clotting of blood
         [syn: {vitamin K}, {naphthoquinone}, {antihemorrhagic
         factor}]

from The Collaborative International Dictionary of English v.0.48

vitamin K \vitamin K\ n. (1929) [from G. Koagulationsvitamin.]
   either of two fat-soluble vitamins (vitamin K1 or vitamin K2)
   that help clot blood by participating in the fromation of
   prothrombin.

   Syn: naphthoquinone.
        [WordNet 1.5 +PJC]