\ri-▐zist\ n (1836) (1) In preparing zinc printing plates, a material, such as wax, that covers the areas of the plate that are not to be etched by acid (acid resist); or, in electroplating, a material that covers areas that are not to be plated. (2) In photolithography and microlithography, widely used in making solid-state electronic devices and printed circuits, a thin film, applied over a substrate, whose solubility in a developer solvent is reduced (negative resist) or enhanced (positive resist) by exposure to UV or other radiation. In polymeric resists, the mechanism of solubility reduction is crosslinking and of solubility enhancement, chemical reaction or chain scission (Leach RH, Pierce RJ, Hickman EP, Mackenzie MJ, Smith HG (1993) Printing ink manual, 5th edn. Blueprint, New York; Leach RH, Pierce RJ (eds) (1976) Printing ink handbook. National Association of Printing Ink Manufacturers, Woodbridge, New Jersey).