from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A geometric curve traced by a fixed point on one circle which rotates around the perimeter of another circle. Examples include the shape of the Wankel engine

from the GNU version of the Collaborative International Dictionary of English

  • n. A kind of curve. See epicycloid, any trochoid.

from The Century Dictionary and Cyclopedia

  • n. In geometry, the curve traced by a point in the plane of a circle which rolls on the convex side of a fixed circle.


Sorry, no etymologies found.


  • Mazda's new RX-8 sports car is unusual in its use of the rotary engine invented by Felix Wankel: a triangular rotor inside a combustion chamber that's a particular case of epitrochoid.

    Archive 2003-10-01

  • The _ellipse_, then, is described by these arrangements because it is a special form of the epitrochoid; and various other epitrochoids may be traced with Suardi's pen by substituting other wheels, with different numbers of teeth, for a in Fig. 43.

    Scientific American Supplement, No. 470, January 3, 1885


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