Definition of asteroid in US English:

asteroid

noun

  • 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.

    • ‘So to neglect the problem means that we are vulnerable to asteroid collisions.’
    • ‘Fragments of asteroids and comets pervade interplanetary space.’
    • ‘Ceres was initially considered to be a planet until other asteroids with similar orbits were found.’
    • ‘These glaciers are spotted with craters caused by asteroid impacts.’
    • ‘Dinosaurs may not have been killed off by asteroid impact dust blocking out sunlight, a geologist says.’
    • ‘These scientists also study the natural satellites of other planets as well as asteroids and comets.’
    • ‘It has been suggested that impacts with comets and asteroids provided Earth with much of its water.’
    • ‘Both comets and asteroids are the left-over building blocks of the planets in our solar system.’
    • ‘In our own solar system, asteroids have collided with Earth, the moon and other planets.’
    • ‘It's just that you can't keep quiet about things like asteroid impacts.’
    • ‘Some explanations for extinctions and evolution include strikes by asteroids or comets.’
    • ‘Most of the known asteroids orbit the sun in a belt between Mars and Jupiter.’
    • ‘You can also get asteroid hazard warnings and geomagnetic storm outlooks.’
    • ‘Once an asteroid drifts into either of those regions, it's hard for it to get out.’
    • ‘Our knowledge of comets and asteroids has dramatically improved over the last 20 years.’
    • ‘We know very little about these families of asteroids following the same orbit.’
    • ‘In many ways asteroids and comets are likely to offer more varied and abundant natural resources than the Moon.’
    • ‘Comets and asteroids also contribute to the near-Earth space environment.’
    • ‘Amateur astronomers have made many asteroid, comet, and supernova discoveries.’
    • ‘Our star system is chock full of asteroids and comets, in every conceivable orbit and location.’
    • ‘Most of the larger asteroids and comets are also in stable orbits around the sun.’
    • ‘There may be other families of small asteroids within our solar system that, even now, remain to be discovered.’
    • ‘When the asteroid hit, it was vaporized by the extreme energy of the impact.’
    celestial body, heavenly body, sun
    View synonyms
  • 2Zoology
    An echinoderm of the class Asteroidea; a starfish.

    • ‘Both approaches will shed light on the adaptive significance and functional morphology of asteroids.’
    • ‘The fossil record is a potential source of needed data, although fossil asteroids are rare, and they tend to be poorly preserved.’
    • ‘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.’
    • ‘The asteroid is preserved with the dorsal surface exposed.’

adjective

Zoology
  • Relating to echinoderms of the class Asteroidea.

Origin

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

Pronunciation

asteroid

/ˈastəˌroid//ˈæstəˌrɔɪd/