Webster's 1828 Dictionary
EPICYCLOID
n.[Gr. 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. 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.
EPICYCLOIDAL
a.Pertaining to the epicycloid, or having its properties.
Webster's 1913 Dictionary
EPICYCLOID
Ep `i *cy "cloid, n. Etym: [Epicycle + -oid: cf. F. épicycloïde.](Geom.)
Defn: A curve traced by a point in the circumference of a circle which rolls on the convex side of a fixed circle.
Note: Any point rigidly connected with the rolling circle, but not in its circumference, traces a curve called an epitrochoid. The curve traced by a point in the circumference of the rolling circle when it rolls on the concave side of a fixed circle is called a hypocycloid; the curve traced by a point rigidly connected with the rolling circle in this case, but not its circumference, is called a hypotrochoid. All the curves mentioned above belong to the class class called roulettes or trochoids. See Trochoid.
EPICYCLOIDAL
EPICYCLOIDAL Ep `i *cy *cloid "al, a.
Defn: Pertaining to the epicycloid, or having its properties. Epicycloidal wheel, a device for producing straight-line motion from circular motion, on the principle that a pin fastened in the periphery of a gear wheel will describe a straight line when the wheel rolls around inside a fixed internal gear of twice its diameter.
New American Oxford Dictionary
epicycloid
ep i cy cloid |ˌepiˈsīˌkloid ˌɛpəˈsaɪklɔɪd | ▶noun Mathematics a curve traced by a point on the circumference of a circle rolling on the exterior of another circle. DERIVATIVES ep i cy cloi dal |-sīˈkloidl |adjective
Oxford Dictionary
epicycloid
epicycloid |ˌɛpɪˈsʌɪklɔɪd | ▶noun Mathematics a curve traced by a point on the circumference of a circle rolling on the exterior of another circle. DERIVATIVES epicycloidal |-ˈklɔɪd (ə )l |adjective
The Wordsmith Dictionary