Catacaustic

The curve which is the Envelope of reflected rays.

Cardioid	Cusp of Cardioid	Nephroid
Circle	not on Circumference	Limaçon
Circle	on Circumference	Cardioid
Circle	point at $\infty$	Nephroid
Cissoid of Diocles	Focus	Cardioid
one arch of a Cycloid	rays Perpendicular axis	two arches of a Cycloid
Deltoid	point at infinity	Astroid
$\ln x$	rays Parallel axis	Catenary
Logarithmic Spiral	Origin	equal Logarithmic Spiral
Parabola	rays Perpendicular axis	Tschirnhausen Cubic
Quadrifolium	center	Astroid
Tschirnhausen Cubic	Focus	Semicubical Parabola

See also Caustic, Diacaustic

References

Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 60 and 207, 1972.