niello

n. [ It. niello, LL. nigellum a black of blackish enamel, fr. L. nigellus, dim. of niger black. See Negro, and cf. Anneal. ] 1. A metallic alloy of a deep black color. [ 1913 Webster ]

2. The art, process, or method of decorating metal with incised designs filled with the black alloy. [ 1913 Webster ]

3. A piece of metal, or any other object, so decorated. [ 1913 Webster ]

4. An impression on paper taken from an ancient incised decoration or metal plate. [ 1913 Webster ]

5. An impression on paper taken from the engraved or incised surface before the niello alloy has been inlaid. [ Webster 1913 Suppl. ]