gypsum Meaning, Definition & Usage

  1. noun a common white or colorless mineral (hydrated calcium sulphate) used to make cements and plasters (especially plaster of Paris)

WordNet

Gyp"sum noun
Etymology
L. gypsum, Gr. cf. Ar. jibs plaster, mortar, Per. jabsn lime.
Definitions
  1. (Min.) A mineral consisting of the hydrous sulphate of lime (calcium). When calcined, it forms plaster of Paris. Selenite is a transparent, crystalline variety; alabaster, a fine, white, massive variety.

Webster 1913