An epicycle in addition to the hypocycle was introduced into Mercury's orbit.
To help out of this difficulty, the worst possible mechanical scheme was invented, that known as the epicycle.
In this epicycle he was not supposed to revolve, but to librate, or move up and down in its diameter.
For the epicycle is a sphere which changes place in the circumference of the large sphere.
With centric and eccentric scribbled o'er, / Cycle and epicycle, orb in orb.
epicycle, ep′i-sī-kl, n. a circle having its centre on the circumference of a greater circle on which it moves.
He imagined that the moon's path round the earth was a fixed combination of cycle and epicycle.
The circle Dd, described by D, the centre of the epicycle, was called the deferent.
The planet is supposed to move equably in the epicycle, and to be carried by the Sun unequably in the proportion of the distances.
epicycle, a conception of the ancient astronomy used to explain the irregular, and at times retrograde, motions of the planets.