- noun a common sedimentary rock, formed of calcium minerals and often containing fossilised shells of sea animals. It is porous in its natural state and may form large caves by being weathered by water. It is used in agriculture and building.
- A sedimentary rock composed mostly of calcium carbonate, calcium, or dolomite. Limestone can be used as a building stone, with its commercial grades being A. Statuary, B. select, C. standard, D. Rustic, E. variegated, and F. Old gothic. It is also crushed into aggregate, crushed for agricultural lime, or burned to produce lime.