Word Study
Gypsum
CIDE DICTIONARY
Gypsum, n. [L. gypsum, Gr. gy`psos; cf. Ar. jibs plaster, mortar, Per. jabs lime.].
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. [1913 Webster]
OXFORD DICTIONARY
Gypsum, n. a hydrated form of calcium sulphate occurring naturally and used to make plaster of Paris and in the building industry.
Derivative
gypseous adj. gypsiferous adj.
Etymology
L f. Gk gupsos
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