Epicycle

A circle, whose center moves round in the circumference of a greater circle; or a small circle, whose center, being fixed in the deferent of a planet, is carried along with the deferent, and yet, by its own peculiar motion, carries the body of the planet fastened to it round its proper center.

A circle which rolls on the circumference of another circle, either externally or internally.

a circle that rolls around (inside or outside) another circle; generates an epicycloid or hypocycloid