enamel

A smooth, glossy material made by fusing glass to a prepared surface, usually of metal. The term is also applied to any object made with, or decorated by, this material. The study of enamelling belongs mainly to the history of jewellery and the decorative arts, but in the Middle Ages enamel was sometimes used for major works, notably Nicolas of Verdun's Klosterneuburg Altar.

Today the word `enamel' is loosely used of any glossy protective covering such as durable paint or varnish applied to the surface of objects made from metal, wood, etc.