magnesium sulphate
(US magnesium sulfate) Chemistry
noun
A soluble white crystalline substance, MgSO4, which occurs in various minerals such as epsomite and kieserite, and is used medicinally as a laxative and anticonvulsant, and as a fertilizer.
Origin
Late 19th century; earliest use found in Henry Roscoe (1833–1915), chemist and university administrator.