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asteroid Syllabification: as·ter·oid
Pronunciation: /ˈastəˌroid/

Definition of asteroid in English:


1A small rocky body orbiting the sun. Large numbers of these, ranging in size from nearly 600 miles (1,000 km) across (Ceres) to dust particles, are found (as the asteroid belt) especially between the orbits of Mars and Jupiter, though some have more eccentric orbits, and a few pass close to the earth or enter the atmosphere as meteors.
Example sentences
  • Ceres was initially considered to be a planet until other asteroids with similar orbits were found.
  • Most of the known asteroids orbit the sun in a belt between Mars and Jupiter.
  • These scientists also study the natural satellites of other planets as well as asteroids and comets.
2 Zoology An echinoderm of the class Asteroidea; a starfish.
Example sentences
  • The asteroid is preserved with the dorsal surface exposed.
  • Available morphological data suggest no ecologic parameters that would be unusual among living asteroids.
  • An unpaired commonly enlarged interbrachial ossicle, the axillary, occurs in most Paleozoic asteroids, including those treated here.


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Zoology Relating to echinoderms of the class Asteroidea.


Pronunciation: /ˌastəˈroidl/
Example sentences
  • The Hubble Space Telescope captured a picture of starlit asteroidal and cometary debris encircling the yellow dwarf star HD 107146.
  • These satellites range in size from small on the asteroidal scales, to nearly as large as Saturn's moon Mimas.
  • Our understanding of astronomy has shown us that cometary and asteroidal impacts are relatively commonplace over timescales of hundreds of millions of years.


Early 19th century: from Greek asteroeidēs 'starlike', from astēr 'star'.

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