·noun A curved formed by the consecutive intersections of rays of light refracted through a lens.
II. Diacaustic ·noun That which burns by refraction, as a double convex lens, or the sun's rays concentrated by such a lens, sometimes used as a cautery.
III. Diacaustic ·adj Pertaining to, or possessing the properties of, a species of caustic curves formed by refraction. ·see Caustic surface, under Caustic.