noun epicycle A small circle whose center moves around the circumference of a larger one. 1
noun epicycle (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 0
noun epicycle a circle that rolls around the inside or outside of another circle, so generating an epicycloid or hypocycloid 0
noun epicycle a circle whose center moves along the circumference of another, larger circle 0
noun epicycle a circle which generates a hypocycloid or epicycloid by rolling around the circumference of a fixed circle 0
noun epicycle (astronomy) A small circle whose centre is on the circumference of a larger circle; in Ptolemaic astronomy it was seen as the basis of revolution of the "seven planets", given a fixed central Earth. 0
noun epicycle (mathematics) Any circle whose circumference rolls around that of another circle, thus creating a hypocycloid or epicycloid. 0
