What does "epicyclic" mean?

Epicyclic: Pertaining to, resembling, or having the motion of, an epicycle. Epicyclic train (Mach.), a train of mechanism in which epicyclic motion is involved; esp., a train of spur wheels, bevel wheels, or belt pulleys, in which an arm, carrying one or more of the wheels, sweeps around a center lying in an axis common to the other wheels.