HYPOCYCLOID

hypocycloid

(noun) a line generated by a point on a circle that rolls around inside another circle

Source: WordNet® 3.1

Etymology

Noun

hypocycloid (plural hypocycloids)

(geometry) The locus of a point on the circumference of a circle that rolls without slipping inside the circumference of another circle.

Source: Wiktionary

Hy`po*cy"cloid, n. Etym: [Pref. hypo- + cycloid: cf. F. hypocycloïde.] (Geom.)

Definition: A curve traced by a point in the circumference of a circle which rolls on the concave side in the fixed circle. Cf. Epicycloid, and Trochoid.

Source: Webster’s Unabridged Dictionary 1913 Edition