The Collaborative International Dictionary of English v.0.48:

patina \pat"ina\ (p[a^]t"[i^]*n[.a]; It. p[aum]"t[-e]*n[.a]), 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.
      [1913 Webster]

   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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

patina
    n 1: a fine coating of oxide on the surface of a metal

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "patina":
   burnish, coat, coating, collop, covering, cut, deal, disk, feuille,
   film, finish, flap, foil, fold, glaze, gloss, lamella, lamina,
   laminated glass, laminated wood, lap, leaf, luster, membrane, pane,
   panel, patination, peel, pellicle, plait, plank, plate, plating,
   ply, plywood, polish, rasher, safety glass, scum, sheet, shine,
   skin, slab, slat, slice, table, tablet, veneer, verdigris, wafer