Tschirnhausen cubic

Etymology
Named after  (1651–1708), German mathematician, physicist, physician, and philosopher. The name was first used in a 1900 paper by R. C. Archibald.

Noun

 * 1)  A plane curve defined, in its left-opening form, by the polar equation $$r = a\sec^3(\theta/3)$$ where sec is the secant function.