| a white, crystalline, water-insoluble, tasteless powder, CaCO3, occurring in nature in various forms, as calcite, chalk, and limestone: used chiefly in dentifrices and polishes and in the manufacture of lime and cement. |
| calcium carbonate n. A colorless or white crystalline compound, CaCO3, occurring naturally as chalk, limestone, marble, and other forms and used in a wide variety of manufactured products including commercial chalk, medicines, and dentifrices. |