# Epicyclic

[ep-uh-sahy-kuh l] /ˈɛp əˌsaɪ kəl/

**noun**

1.

Astronomy. a small circle the center of which moves around in the circumference of a larger circle: used in Ptolemaic astronomy to account for observed periodic irregularities in planetary motions.

2.

Mathematics. a circle that rolls, externally or internally, without slipping, on another circle, generating an or hypocycloid.

/ˈɛpɪˌsaɪkəl/

**noun**

1.

(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.

a circle that rolls around the inside or outside of another circle, so generating an epicycloid or hypocycloid

n.

late 14c., from Latin epicyclus, from Greek epikyklos, from epi (see epi-) + kyklos (see cycle (n.)).

epicycle

(ěp’ĭ-sī’kəl)

Tagged: e

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noun, Machinery. 1. a train of gears or pulleys in which one or more of the axes revolve about a central axis. noun 1. a cluster of gears consisting of a central gearwheel with external teeth (the sun), a coaxial gearwheel of greater diameter with internal teeth (the annulus), and one or more planetary gears […]

- Epicycloid
[ep-uh-sahy-kloid] /ˌɛp əˈsaɪ klɔɪd/ noun, Geometry. 1. 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 […]

- Epicycloidal-gear
noun 1. one of the gears of an epicyclic train.

- Epicycloidal wheel
noun 1. one of the planetary gears of an epicyclic train