asteroid
n. countablen. a large rock or metal object that orbits the sun. You use this word for space rocks that are smaller than planets but larger than meteors.
n. a small, rocky body orbiting the sun, typically composed of stone and metal. Distinct from comets, which contain ice and dust.
An asteroid hit the moon last night.
Scientists track large asteroids to ensure none will collide with Earth in the coming decades.
The discovery of a new asteroid belt between Mars and Jupiter reshaped our understanding of how the solar system formed billions of years ago.
From aster + -oid, lit. "star-like". Coined by William Herschel.
Borrowed from Ancient Greek ἀστεροειδής (asteroeidḗs), from ἀστήρ (astḗr, “star”) + εἶδος (eîdos, “form”). Analyzable as aster- + -oid. Piecewise doublet of etymology 1. Compare also the botanical taxon Asteroideae.