epicycloid
(ɛpɪˈsaɪklɔɪd)
[f. epicycle + -oid.]
A curve generated by a point in the circumference of a moveable circle, which revolves on that of a fixed circle; in accurate phraseology the term is now limited to the case in which the moveable circle rolls on the exterior of the other (formerly exterior epicycloid); the name hypocycloid being employed for what was formerly called the interior epicycloid.
| c 1790 J. Imison Sch. Art i. 36. 1816 J. Smith Panorama Sc. & Art I. 356 The acting faces of the leaves of the pinion should be parts of an interior epicycloid..and the acting surfaces of the teeth of the wheel should be portions of an exterior epicycloid. 1884 F. J. Britten Watch & Clockm. 289 The action should be confined as nearly as possible to the epicycloid on the wheel. |