A hypocycloid – the path of a point on a circle rolling inside another circle – for which the radius of the inner circle is four times smaller than that of the larger circle; this ratio results in the astroid having four cusps. The astroid was first studied by the Danish astronomer Ole R...
Star-shaped. ... Origin: G. Astroeides, fr. Astron, star, + eidos, resemblance ... (05 Mar 2000) ... 
Type: Term Pronunciation: as′troyd Definitions: 1. Star-shaped.
a hypocycloid with four cusps.