any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)
"The newly discovered asteroid passed safely through the gap between the orbits of Mars and Jupiter."
Any member of the taxonomic class Asteroidea; a starfish
"The newly discovered asteroid zipped silently around our sun, much larger than any meteorite but far too small to be classified as a planet."
A naturally occurring solid object, which is smaller than a planet and is not a comet, that orbits a star
shaped like a star
"The ancient Greeks named that bright rock floating in space an asteroid because its irregular shape reminded them of a jagged star."
The word comes from the Greek words aster and -oid, literally meaning "star-like." It was coined by the astronomer William Herschel.