The Collaborative International Dictionary of English v.0.48:

Zocor \Zo"cor\ (z[=o]"k[^o]r), n. [Trade name from Merck & Co.]
   a trade name for simvastatin.
   [PJC]

WordNet (r) 3.0 (2006):

Zocor
    n 1: an oral lipid-lowering medicine (trade name Zocor)
         administered to reduce blood cholesterol levels;
         recommended after heart attacks [syn: simvastatin,
         Zocor]