Epsom salts \Ep"som salts`\ or Epsom salt \Ep"som salt`\ (Med.)
Sulphate of magnesia having cathartic qualities; --
originally prepared by boiling down the mineral waters at
Epsom, England, -- whence the name; afterwards prepared from
sea water; but now from certain minerals, as from siliceous
hydrate of magnesia.
[1913 Webster]