epicycle noun. ['ɛpɪsʌɪk(ǝ)l] LME.
[Old & mod. French épicycle or late Latin epicyclus from Greek epikuklos, formed as EPI- + kuklos circle.]
A circle whose centre moves round the circumference of a larger circle; spec. (History of Science) such a circle in the Ptolemaic system, in which the planets were regarded as moving in circles whose centres moved round larger circles (deferents) centred on the earth.

■ epicyclic [-'sʌɪk-, -'sɪk-] adjective & noun (a) adjective of, pertaining to, or involving epicycles; designating a gear in which one wheel travels round the outside or the inside of another wheel with which it meshes; (b) noun an epicyclic gear: M19.

■ epicyclical [-'sʌɪk-, -'sɪk-] adjective = epicyclic adjective M19.

[TahlilGaran] English Dictionary ▲