epitrochoid

American  

[ep-i-troh-koid] / ˌɛp ɪˈtroʊ kɔɪd /

Geometry.

1. a plane curve generated by the motion of a fixed point on the radius or extension of the radius of a circle that rolls externally, without slipping, on a fixed circle. The epitrochoid is a generalization of the epicycloid.

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Etymology

Origin of epitrochoid

First recorded in 1835–45; epi- + trochoid