One of the constituents of animal fats and also of some
   vegetable fats, as the butter of cacao. It is especially characterized
   by its solidity, so that when present in considerable quantity it
   materially increases the hardness, or raises the melting point, of the
   fat, as in mutton tallow. Chemically, it is a compound of glyceryl with
   three molecules of stearic acid, and hence is technically called
   tristearin, or glyceryl tristearate.