Definition of: aging

(ā′jing) noun
1. The process of acquiring characteristics of age.
2. Biol. The progressive breakdown of an organism or any of its parts through the cumulative effects of irreversible physicochemical changes acting over a period of time.
3. The effects of time on the properties of materials or substances.
4. Any means for obtaining such effects artificially, as the weathering of clay for bricks, or the acid treatment of bronze to obtain a patina.
5. Metall. A change in the properties of certain metals, as hardness and tensile strength, caused by heat treatment and cold working.
6. A method of steaming fabrics to develop and fix the colors. Also spelled ageing.