a surface that envelopes the light rays reflected or refracted by a curved surface
another name for caustic (sense 4)
caustic surface in American English
noun
Optics
the surface to which all light rays emanating from a single point and reflected by a curved surface, as a concave mirror, are tangent
Also called: caustic
Word origin
[1865–70]This word is first recorded in the period 1865–70. Other words that entered Englishat around the same time include: dunk, goulash, springboard, steamroller, tick-tack-toe