n. Change of substance; conversion of one substance into another.n. In pathology, the production of local disease in some part of the body from a focus of more or less similar disease in some other part not immediately adjacent.n. In botany, metabolism.n. In petrography, a change within a rock or mineral in the nature of recrystallization or molecular rearrangement, without the addition or subtraction of material: as the crystallization of a limestone, or the devitrification of glass.