Douglas Harper's Etymology Dictionary
"star-shaped," 1897, from Greek astroeides, from astron "star" (see astro-) + -oeides (see -oid).
Wiktionary
n. (context geometry English) A hypocycloid with four cusps.
Wikipedia
An astroid is a particular mathematical curve: a hypocycloid with four cusps. Specifically, it is the locus of a point on a circle as it rolls inside a fixed circle with four times the radius. By double generation, it is also the locus of a point on a circle as it rolls inside a fixed circle with 4/3 times the radius. It can also be defined as the envelope of a line segment with an end point on each of the axes. It is therefore the envelope of the moving bar in the Trammel of Archimedes.
Its modern name comes from the Greek word for " star". The curve had a variety of names, including tetracuspid (still used), cubocycloid, and paracycle. It is nearly identical in form to the evolute of an ellipse.
Usage examples of "astroid".
Indeed, Private Storm was gifted, but now such talents would be wasted on clearing astroid belts for hyperspace travel.
Skywalker nodded toward a field of tumbling astroids and angled the TIE bomber toward them.
Blue Three and Blue Six reported chasing a TIE bomber into the far astroid field but our sensors don't pick up anything due to interference.