aging

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The process of growing old or maturing.
• noun An artificial process for imparting the characteristics and properties of age.

from The Century Dictionary.

• noun In the preparation of logwood for dyeing, the process of exposing the wood (usually in the form of chips) to the air, in order that the hematoxylin it, contains may be oxidized or developed into hematein, the actual coloring agent. Also known as curing or maturing.
• noun In electricity, the property, exhibited more or less by iron, of showing an increase of hysteresis loss when for a long time exposed to alternating magnetization, especially at a higher temperature.
• noun Any process for imparting the characteristics and properties of age: as, the aging of wines and liquors by heat and agitation.
• noun In calicoprinting and dyeing, the process of fixing the soluble mordant or dye by exposing the cloth in well-ventilated chambers to air which is kept warm and moist, for a time sufficient to allow the mordant or dye laid upon the surface of the cloth to penetrate the fibers and become firmly attached to them. Any superfluous portions, or those which may remain soluble, are removed by dunging
• noun .—3. In ceramics, the storage of prepared clay, to allow it time to ferment and ripen before using. E. H. Knight.
• noun Also spelled ageing.

from the GNU version of the Collaborative International Dictionary of English.

• noun the process by which objects or materials acquire desirable qualities by being left undisturbed for some time under specific conditions. It is used mostly for foods snd beverages, but also for other materials.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb Present participle of age.
• noun intransitive The process of becoming older or more mature.
• noun transitive Allowing something to become older.
• noun transitive The deliberate act of making something (such as an antique) appear older than it is.
• noun gerontology Becoming senescent; accumulating damage to macromolecules, cells, tissues and organs with the passage of time
• noun euphemistic Elderly person. Only as a collective plural in "the aging"
• adjective Becoming elderly.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the organic process of growing older and showing the effects of increasing age
• adjective growing old
• noun acquiring desirable qualities by being left undisturbed for some time