epicycloid

[ ep-uh-sahy-kloid ]
/ ˌɛp əˈsaɪ klɔɪd /
|

noun Geometry.

a curve generated by the motion of a point on the circumference of a circle that rolls externally, without slipping, on a fixed circle. Equation: x = (a + b) cos(θ) − b cos[(a + b)θ/b] and y = (a + b) sin(θ) − b sin[(a + b)θ/b].

Nearby words

  1. epicureous,
  2. epicurus,
  3. epicuticle,
  4. epicycle,
  5. epicyclic train,
  6. epicycloidal gear,
  7. epicycloidal wheel,
  8. epicystitis,
  9. epicystotomy,
  10. epidaurus

Compare epitrochoid.

Origin of epicycloid

First recorded in 1780–90; epicycle + -oid

Related formsep·i·cy·cloi·dal, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for epicycloid

epicycloid

/ (ˌɛpɪˈsaɪklɔɪd) /

noun

the curve described by a point on the circumference of a circle as this circle rolls around the outside of another fixed circle, the two circles being coplanarCompare hypocycloid, cycloid (def. 4)
Derived Formsepicycloidal, adjective

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for epicycloid

epicycloid

[ ĕp′ĭ-sīkloid′ ]

The curve described by a point on the circumference of a circle as the circle rolls on the outside of the circumference of a second, fixed circle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.