Meaning of Epsom salt

Ep'som salt"

Pronunciation: [key]
  1. Often,hydrated magnesium sulfate, MgSO&multiplydot;7HO, occurring as small colorless crystals: used in fertilizers, the dyeing of fabrics, leather tanning, etc., and in medicine chiefly as a cathartic.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.