D defs.my
Entry 1 sense Webster, 1913

Hypotrochoid

· Hy·po·tro·choid · IPA /ˌhaɪ.poʊˈtɹoʊ.kɔɪd/
01 n. A curve, traced by a point in the radius, or radius produced, of a circle which rolls upon the concave side of a fixed circle. See Hypocycl…
  1. 1.
    A curve, traced by a point in the radius, or radius produced, of a circle which rolls upon the concave side of a fixed circle. See Hypocycloid, Epicycloid, and Trochoid.(Geom.) See: Hypocycloid, Epicycloid, Trochoid