planetoid vs asteroid

planetoid and asteroid both are nouns.

Word	Noun	Adjective	Verb	Adverb
planetoid	Yes	No	No	No
asteroid	Yes	Yes	No	No

As nouns, asteroid is a hyponym of planetoid; that is, asteroid is a word with a more specific, narrower meaning than planetoid:

planetoid: any of numerous small celestial bodies that move around the sun
asteroid: any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)

Other hyponyms of planetoid include KBO, Kuiper belt object.

planetoid (noun)	asteroid (noun)
any of numerous small celestial bodies that move around the sun	any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)

planetoid (adjective)	asteroid (adjective)
	shaped like a star