The definition of an asteroid is a rocky mass that orbits the sun.
A small planet whose orbit is between Mars and Jupiter is an example of an asteroid.
See asteroid in Webster's New World College Dictionary
adjective
Origin: Gr asteroeidēs < astēr, star + eidēs, -oid
noun
See asteroid in American Heritage Dictionary 4
noun
Origin:
Origin: From Greek asteroeidēs, starlike
Origin: : astēr, star; see ster-3 in Indo-European roots
Origin: + -oeidēs, -oid
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