To produce, as figures or designs, on mental, glass, or the like, by means of lines or strokes eaten in or corroded by means of some strong acid. Note: The plate is first covered with varnish, or some other ground capable of resisting the acid, and this is then scored or scratched with a needle, or similar instrument, so as to form the drawing; the plate is then covered with acid, which corrodes the metal in the lines thus laid bare.