Source : Webster's Revised Unabridged Dictionary (1913)

Mercurous \Mer*cu"rous\, a. (Chem.)
   Of, pertaining to, or derived from, mercury; containing
   mercury; -- said of those compounds of mercury in which it is
   present in its highest proportion.

   {Mercurous chloride}. (Chem.) See {Calomel}.

Source : WordNet®

mercurous chloride
     n : a tasteless colorless powder used medicinally as a cathartic
         [syn: {calomel}]