Definition of "catacaustic" []

• A caustic curve formed by light reflecting from a curved surface (noun)
• 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 (noun)

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• "You know the ordinary nephroid as the reflected catacaustic of a circle, the involute of Caley’s sextic, and a generally good-natured two-cusped epicycloid."