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epicycle

Syllabification: ep·i·cy·cle
Pronunciation: /ˈepəˌsīk(ə)l
 
/

Definition of epicycle in English:

noun

Geometry
1A small circle whose center moves around the circumference of a larger one.
Example sentences
  • The historically older concept of epicycles (small cycles on a bigger cycle) has not found use in the geological literature.
  • Other threads appeared out of nowhere, forming, with epicycles and Celtic knotting, a mesh bag that pulled him irresistibly toward the bleak globe that was the Inquisitor.
  • Waves come in like epicycles rippling through the larger cycles of tides, and the moon's revolution around the Earth, and the Earth's revolution around the sun.
1.1 historical An epicycle used to describe planetary orbits in the Ptolemaic system.
Example sentences
  • A planet moves uniformly on a circle called an epicycle, and the epicycle in turn moves uniformly on a circle called the deferent.
  • For example, each planet was said to move in its own small curve called an epicycle, while all the epicycles moved around the earth in larger circles called deferents.
  • Although orbits were discussed by the Greeks they were attempting to derive orbits for the planets round the Earth so are of little interest to us in this article although the method of epicycles is an early application of Fourier series.

Origin

late Middle English: from Old French, or via late Latin from Greek epikuklos, from epi 'upon' + kuklos 'circle'.

Derivatives

epicyclic

1
Pronunciation: /ˌepiˈsīklik, ˈepi-/
adjective
Example sentences
  • It is based on the epicyclic and eccentric models of planetary motion.
  • Collectively Kepler's Laws superseded the ancient Ptolemaic concept of a spherical universe with epicyclic motion.
  • The key to the technology lies in the combination of a patented epicyclic traction transmission and electric gear ratio control.

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