The Collaborative International Dictionary of English v.0.48:

calciferol \cal*cif"er*ol\ n.
   one of the forms of vitamin D, a fat-soluble vitamin that
   prevents rickets. It is an unsaturated alcohol, C28H43OH
   found in foods such as milk and fish liver oils. It is used
   as a dietary supplement in milk.

   Syn: vitamin D, ergocalciferol, cholecarciferol, D.
        [WordNet 1.5 +PJC]