Source : Webster's Revised Unabridged Dictionary (1913)

Patina \Pat"ina\, n. [It., fr. L. patina a dish, a pan, a kind
   of cake. Cf. {Paten}.]
   1. A dish or plate of metal or earthenware; a patella.

   2. (Fine Arts) The color or incrustation which age gives to
      works of art; especially, the green rust which covers
      ancient bronzes, coins, and medals. --Fairholt.

Source : WordNet®

patina
     n : a fine coating of oxide on the surface of a metal
     [also: {patinae} (pl)]