Hypotrochoid
Pronunciation : Hy`po*tro"choid
Part of Speech : n.
Etymology : [Pref. hypo- + trochoid.] (Geom.)
Definition : Defn: 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.
Source : Webster's Unabridged Dictionary, 1913