\Di`a*caus"tic\, 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}.

\Di`a*caus"tic\, 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.
2. (Math.) A curved formed by the consecutive intersections
   of rays of light refracted through a lens.