Definition of diacaustic

• a. - Pertaining to, or possessing the properties of, a species of caustic curves formed by refraction. See Caustic surface, under Caustic.
• n. - 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.
• n. - A curved formed by the consecutive intersections of rays of light refracted through a lens.