cycloid

[ sahy-kloid ]

adjective

1. resembling a circle; circular.
2. (of the scale of a fish) smooth-edged, more or less circular in form, and having concentric striations.
3. (of a fish) having such scales.
4. Psychiatry. of or noting a personality type characterized by wide fluctuation in mood within the normal range.

noun

1. a cycloid fish.
2. Geometry. a curve generated by a point on the circumference of a circle that rolls, without slipping, on a straight line.

cycloid

/ ˈsaɪklɔɪd /

adjective

1. resembling a circle
2. (of fish scales) rounded, thin, and smooth-edged, as those of the salmon
3. psychiatry (of a type of personality) characterized by exaggerated swings of mood between elation and depression See also cyclothymia

noun

1. geometry the curve described by a point on the circumference of a circle as the circle rolls along a straight line Compare trochoid
2. a fish that has cycloid scales

cycloid

/ sī′kloid′ /

1. Resembling a circle.
2. Thin, rounded, and smooth-edged, like a disk. Used of fish scales.
3. The curve traced by a point on the circumference of a circle that rolls on a straight line.

Derived Forms

• cyˈcloidal, adjective
• cyˈcloidally, adverb

Other Words From

• cy·cloidal adjective
• cy·cloidal·ly adverb

Word History and Origins

Origin of cycloid¹

First recorded in 1655–65, cycloid is from the Greek word kykloeidḗs like a circle. See cycl-, -oid

Example Sentences

In brief—distinct grounds, and vivid circular or cycloid figures, of no meaning, are here Median laws.

From Project Gutenberg

In 1644 he published a tract on the properties of the cycloid in which he suggested a solution of the problem of its quadrature.

From Project Gutenberg

Other sharks had piercing teeth (Cladoselache and Cladodus); some, the petalodonts, had peculiar cycloid cutting teeth.

From Project Gutenberg

The tail is diphycercal in all, ending in a long point, and the body is covered with cycloid scales.

From Project Gutenberg

The Holoptychiidæ have the pectoral fins acute, the scales cycloid, enameled, and the teeth very complex.

From Project Gutenberg