• (a.) Pertaining to a planetoid.
Plan'et·oid·al adjective Pertaining to a planetoid. 
planetoid, planetoidal 1. A branch of astronomy that studies the origin and composition of the planets and other solid bodies in the solar system such as comets and meteors; asteroid. 2. A body resembling a planet; a name sometimes given to the minor planets or asteroids. 3. Of or belonging to the astroids.