n. In chem., a compound formed by the union of carbonic acid with a base: as, calcium carbonate; copper carbonate.n. plural The common name in the Cordilleran mining region of ores consisting in large part of carbonate of lead. and usually containing silver. This is an important class of ores in Colorado and Utah.n. Same as carbonado or bort.To impregnate or saturate with carbonic acid.