a. [ Pref. dia- + caustic. ] (Opt.) Pertaining to, or possessing the properties of, a species of caustic curves formed by refraction. See Caustic surface, under Caustic. [ 1913 Webster ]

n. 1. (Med.) 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. [ 1913 Webster ]

2. (Math.) A curved formed by the consecutive intersections of rays of light refracted through a lens.