Diacaustic /(?)/

Di·a·caus·tic

Diacaustic

a.
  1. Pertaining to, or possessing the properties of, a species of caustic curves formed by refraction. See Caustic surface, under Caustic. (Opt.)

Diacaustic

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