the curve described by a point on the circumference of a circle as this circle rolls around the outside of another fixed circle, the two circles being coplanar
Compare hypocycloid, cycloid (sense 4)
Derived forms
epicycloidal (ˌepicyˈcloidal)
adjective
epicycloid in American English
(ˌɛpəˈsaɪˌklɔɪd)
noun
Geometry
the curve traced by a point on the circumference of an epicycle that rolls around the outside of a fixed circle