patina

(pătˈn-ə)

(pătˈn-ə, pə-tēˈnə) also pa·tine (pă-tēnˈ)

1. A thin greenish layer, usually basic copper sulfate, that forms on copper or copper alloys, such as bronze, as a result of corrosion.
2. The sheen on any surface, produced by age and use.
3. A change in appearance produced by long-standing behavior, practice, or use: a face etched with a patina of fine lines and tiny wrinkles.