Asteroid

Part of speech: noun

Pronunciation: /ˈæst(ə)ɹɔɪd/

Definitions

1. A small rocky body that orbits the sun, typically found in a belt between Mars and Jupiter, or any similar celestial object composed primarily of rock and metal
2. A celestial object made of rock and metal that orbits the sun primarily between Mars and Jupiter, and which can vary in size and shape
3. A small, irregularly-shaped rocky body that travels through space in an orbit around the sun, predominantly located in a region between Mars and Jupiter

Etymology: William Herschel, the German-born astronomer working in England, named the first of these objects in 1802, and the name came from a friend rather than from his own pen. Classical scholar Charles Burney Jr., son of the music historian Charles Burney, suggested it. Herschel had just found a small body between Mars and Jupiter that looked like a star, not the fuzzy disc planets showed through a telescope, and the word was built to say exactly that. The coinage draws on Ancient Greek "asteroeidēs", meaning "starlike", formed from "astēr" (star) and "eidos" (form, shape). The Greek ending "-oid" survives in English words like "android" and "humanoid", where it means "resembling". So the word literally describes something that looks like a star. The name is a learned coinage rather than an old word passed down through speakers. The same Greek roots give the botanical name "Asteroideae" for a large group of flowering plants, the daisy family, whose flower heads also look star-shaped.

Synonyms: planetoid, minor planet