catacaustic

from The Century Dictionary.

• In geometry, belonging to caustic curves formed by reflection.
• noun In optics, a caustic curve formed by the reflection of the rays of light: so called to distinguish it from the diacaustic, which is formed by refracted rays. See caustic, n., 3.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Physics) Relating to, or having the properties of, a caustic curve formed by reflection. See caustic, a.
• noun (Physics) A caustic curve formed by reflection of light.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a caustic curve formed by light reflecting from a curved surface
• noun mathematics the envelope of all rays that emanate from a specified point (the radiant point) and reflect from a given curve; the evolute of the orthotomic