graffito

n. [ It., fr. graffio a scratching. ] 1. (Art) Production of decorative designs by scratching them through a surface of layer plaster, glazing, etc., revealing a different-colored ground; also, pottery or ware so decorated; -- chiefly used attributively. [ Webster 1913 Suppl. ]

2. the singular form of graffiti, seldom used. [ PJC ]