Emily Dickinson Lexicon

EP-I-CY'CLOID, n. [Gr. επικυκλοειδης; επι, κυκλος, and ειδος, 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. Encyc. Harris. 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. Ed. Encyc.