Verdigris n. : A green poisonous substance used as a pigment and drug, obtained by the action of acetic acid on copper, and consisting essentially of a complex mixture of several basic copper acetates.

Verdigris n. : The green rust formed on copper.

Verdigris v. t. : To cover, or coat, with verdigris.

Example:
How do I remove Verdigris (green gunk) from vintage jewelry?

Taxonomy
Verdigris, pigment, copper, paintings, free encyclopedia, oil paint, stable, acetate, basic copper carbonate, pot, lightfast, resinate, basic copper, acetic acid, Etymology, copper acetate, copper oxide, search.

Defination from the web:
Verdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over ... The name Verdigris comes from the Middle English vertegrez, from the Old French verte grez, an alteration of vert-de-Grèce ("green of Greece" ...