1. Astronomy Any of numerous small solar system bodies that revolve around the sun, with orbits lying chiefly between Mars and Jupiter and characteristic diameters roughly between one and several hundred kilometers. Also called minor planet, planetoid.
2. Zoology See starfish.
adj. also as·ter·oi·dal (ăs′tə-roidl)
[From Greek asteroeidēs, starlike : astēr, star; see ster-3 in the Appendix of Indo-European roots + -oeidēs, -oid.]
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