Definition of "aging"

present participle and gerund of age  examples

The process of becoming older or more mature.  examples

The deliberate process of making something (such as an antique) appear (or, in science fiction, become) older than it is.  examples

(gerontology) The accumulation of damage to macromolecules, cells, tissues and organs with the passage of time; the progressing loss of health, mobility, vibrancy and body functionality, resulting in biological death.

Wear; wear and tear.  examples

Becoming elderly.  examples