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 ]

n. vitamin D2, one of the D vitamins, a group of related substances that prevent rickets.
Syn. -- vitamin D, calciferol, cholecarciferol, D. [ WordNet 1.5 +PJC ]