Definition of lime and its forms clarifies classification for regulatory and commercial use, including hydraulic properties. Lime (calcium oxide) is the monoxide of calcium obtained by removing carbon dioxide from calcium carbonate; commercially it includes quick lime, hydrated lime and hydraulic lime produced by calcining limestone or similar feedstocks. Hydraulic lime contains silica and alumina-derived calcium silicates and aluminates that confer cementitious properties and the ability to set under water. Principal uses include mortar, stucco, plaster, fertilizer and soil stabilisation for road and runway base courses.