EPICYC'LOID, noun [Gr. form.] In geometry, a curve generated by the revolution of the periphery of a circle along the convex or concave side of the periphery of another circle. A curve generated by any point in the plane of a movable circle which rolls on the inside or outside of the circumference of a fixed circle.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI