Hypotrochoid \Hy`po*tro"choid\, n. [Pref. hypo- + trochoid.]
(Geom.)
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}.
[1913 Webster]