Cycloid /(s?"kloid)/

Cy·cloid

Cycloid

n.
  1. 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. (Geom.)

Cycloid

a.
  1. Of or pertaining to the Cycloidei. (Zool.)

Phrases & Compounds
Cycloid scale
a fish scale which is thin and shows concentric lines of growth, without serrations on the margin.

Cycloid

n.
  1. One of the Cycloidei. (Zool.)