Webster's Revised Unabridged Dictionary · 1913

Cycloid

Cycloid (s?"kloid) , noun

[Cyclo- + -oid: compare French cycloide.]

(Geometry) A curve generated by a point in the plane of a circle when the circle is rolled along a straight line, keeping always in the same plane.

The common cycloid is the curve described when the generating point (p) is on the circumference of the generating circle; the curtate cycloid, when that point lies without the circumference; the prolate or inflected cycloid, when the generating point (p) lies within that circumference.

Cycloid , adjective

(Zoology) Of or pertaining to the Cycloidei.
Collocations (1)
Cycloid scale (Zoology) , a fish scale which is thin and shows concentric lines of growth, without serrations on the margin.

Cycloid , noun

(Zoology) One of the Cycloidei.