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

Example Sentences

Sketch the curve known as an epitrochoid, which gives the path of a point on a circle of radius b as it rolls on the outside of a circle of radius a.

From Textbooks • Mar. 30, 2016

Visitors soon learn that the models are see-through likenesses of the Wankel rotary engine�and an epitrochoid, in case they did not know, is the bloated figure-eight shape that its rotor follows when moving.

From Time Magazine Archive