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1. In Ptolemaic cosmology, a small circle, the center of which moves on the circumference of a larger circle at whose center is the earth and the circumference of which describes the orbit of one of the planets around the earth.
2. Mathematics A circle whose circumference rolls along the circumference of a fixed circle, thereby generating an epicycloid or a hypocycloid.

[Middle English epicicle, from Late Latin epicyclus, from Greek epikuklos : epi-, epi- + kuklos, circle; see kwel- in Indo-European roots.]

ep′i·cyc′lic (-sĭk′lĭk, -sī′klĭk) adj.


1. (Astronomy) astronomy (in the Ptolemaic system) a small circle, around which a planet was thought to revolve, whose centre describes a larger circle (the deferent) centred on the earth
2. (Mathematics) a circle that rolls around the inside or outside of another circle, so generating an epicycloid or hypocycloid
[C14: from Late Latin epicyclus, from Greek epikuklos; see epi-, cycle]
epicyclic, ˌepiˈcyclical adj


(ˈɛp əˌsaɪ kəl)

1. a circle whose center moves around in the circumference of a larger circle: used in Ptolemaic astronomy to account for irregularities in planetary motion.
2. a circle that rolls, externally or internally, without slipping, on another circle, generating an epicycloid or hypocycloid.
[1350–1400; Middle English < Middle French < Late Latin epicyclus < Greek epíkyklos. See epi-, cycle]
ep`i•cy′clic (-ˈsaɪ klɪk, -ˈsɪk lɪk) adj.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.epicycle - a circle that rolls around (inside or outside) another circleepicycle - a circle that rolls around (inside or outside) another circle; generates an epicycloid or hypocycloid
circle - ellipse in which the two axes are of equal length; a plane curve generated by one point moving at a constant distance from a fixed point; "he calculated the circumference of the circle"


nEpizykel m
References in classic literature ?
It was gravely said by some of the prelates in the Council of Trent, where the doctrine of the Schoolmen bare great sway, that the Schoolmen were like astronomers, which did feign eccentrics and epicycles, and such engines of orbs, to save the phenomena; though they knew there were no such things; and in like manner, that the Schoolmen had framed a number of subtle and intricate axioms, and theorems, to save the practice of the church.
But when it came to almagest and astrolabe, the counting of figures and reckoning of epicycles, away would go her thoughts to horse and hound, and a vacant eye and listless face would warn the teacher that he had lost his hold upon his scholar.
The city commissioned 400 new projects, including this weekend's Epicycle event (think Cirque du Soleil-style acrobatics within a metal circle of immense scale).
Tenders are invited for epicycle gear forging to drg.
The aim of the work is to obtain analytical and graphical dependences of the efficiency between the driving and the driven links in single-stage single-row and two-row differential gears with closed hydraulic system, when the driving link is the carrier, and the driven one is the epicycle, and vice versa.
Hereafter, when they come to model heav'n And calculate the stars, how they will wield The mighty frame, how build, unbuild, contrive To save appearances, how gird the sphere With centric and eccentric scribbled o'er, Cycle in epicycle, orb in orb.
Even if the centre of the epicycle lay in nearly the same position as it would have in Ptolemy's model, and always moved uniformly with respect to the equant, the circular motion allowed for independent movements too.
Freedman M, 1979c [1974], "An epicycle of Cathay; or, the southward expansion of the sinologists", in The Study of Chinese Society (Stanford University Press, Stanford, CA) pp 39-57
The angular diameter of the Moon was minimum (and hence equal to that of the Sun) when it was at the apogee of its epicycle, i.
According to Novak, inclusive fitness is "somewhat like an epicycle," referring to the Ptolemaic solar system with the Earth at its center.
This then required, and correctly so, that the orbits have epicycle components.
Unlike Ptolemaic astronomy, which purports "to save the appearances" by grafting epicycle onto epicycle, Professor Domingo demonstrates that his global law is a whole that affects all of its constituent parts--namely, the concepts of territoriality, state, sovereignty, and person.