n. a soft grey metallic element of the alkaline earth group occurring naturally in limestone, marble, chalk, etc., that is important in industry and essential for normal growth in living organisms. °Symb.: Ca. calcium carbide a greyish solid used in the production of acetylene. calcium carbonate a white insoluble solid occurring naturally as chalk, limestone, marble, and calcite, and used in the manufacture of lime and cement. calcium hydroxide a white crystalline powder used in the manufacture of plaster and cement; slaked lime. calcium oxide a white crystalline solid from which many calcium compounds are manufactured: also called QUICKLIME, CALX. calcium phosphate the main constituent of animal bones and used as bone ash fertilizer. calcium sulphate a white crystalline solid occurring as anhydrite and gypsum.
[ L CALX lime + -IUM ]