Source : Webster's Revised Unabridged Dictionary (1913)

Calomel \Cal"o*mel\, n. [Gr. ????? beautiful + ????? black. So
   called from its being white, though made from a black mixture
   of mercury and corrosive sublimate. Cf. F. calom['e]las.]
   (Chem.)
   Mild chloride of mercury, {Hg2Cl2}, a heavy, white or
   yellowish white substance, insoluble and tasteless, much used
   in medicine as a mercurial and purgative; mercurous chloride.
   It occurs native as the mineral horn quicksilver.