Any calcarious substance deprived of its fixed or carbonic air, or an earthy substance calcined; as chalk, limestone, oyster-shells, etc.; unslaked lime. Calcarious stones and shells are reduced to quicklime by being subjected for a considerable time to intense heat, which expels the carbonic and aqeuous matter.

Calcium oxide; unslacked lime; -- so called because when wet it develops great heat. See 4th Lime, 2.