gypsum gypsum /ˈdʒɪpsəm/

noun

1. A common white or colorless mineral (hydrated calcium sulphate) used to make cements and plasters (especially plaster of Paris)  ( gypsum )
   a common white or colorless mineral (hydrated calcium sulphate) used to make cements and plasters (especially plaster of Paris)
    Gypsum is a key ingredient in making plaster of Paris.
   Gypsum is a key ingredient in making plaster of Paris.