planet

American  

[plan-it] / ˈplæn ɪt /

noun

1. Astronomy.

   1. Also called major planet.  any of the eight large heavenly bodies revolving about the sun and shining by reflected light: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, or Neptune, in the order of their proximity to the sun. Until 2006, Pluto was classified as a planet ninth in order from the sun; it has been reclassified as a dwarf planet.

   2. a similar body revolving about a star other than the sun.

   3. (formerly) a celestial body moving in the sky, as distinguished from a fixed star, applied also to the sun and moon.

2. Astrology. the sun, moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto: considered sources of energy or consciousness in the interpretation of horoscopes.

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planet British  

/ ˈplænɪt /

noun

1. Also called: major planet.  any of the eight celestial bodies, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, that revolve around the sun in elliptical orbits and are illuminated by light from the sun

2. Also called: extrasolar planet.  any other celestial body revolving around a star, illuminated by light from that star

3. astrology any of the planets of the solar system, excluding the earth but including the sun and moon, each thought to rule one or sometimes two signs of the zodiac See also house

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planet Scientific  

/ plăn′ĭt /

1. In the traditional model of solar systems, a celestial body larger than an asteroid or comet, illuminated by light from a star, such as the Sun, around which it revolves.

2. A celestial body that orbits the Sun, has sufficient mass to assume nearly a round shape, clears out dust and debris from the neighborhood around its orbit, and is not a satellite of another planet. The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was considered to be a planet until its reclassification in 2006 as a dwarf planet. A planetlike body with more than about ten times the mass of Jupiter would be considered a brown dwarf rather than a planet.

3. See also extrasolar planet inner planet outer planet

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planet Cultural  

1. An object in orbit around a star. A planet does not give off its own light; rather, it shines by reflecting sunlight. Planets close to the sun are rocky. Those farther out consist mostly of gas es and liquids.

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Discover More

There are nine major planets, including the Earth, in orbit around our sun, along with many asteroids. (See solar system.)

Scientists have discovered evidence for the existence of many planets that circle other stars.

Etymology

Origin of planet

1250–1300; Middle English planete (< Old French planète ) < Late Latin planēta, planētēs (found only in plural planētae ) < Greek ( astéres ) planḗtai literally, wandering (stars)

Example Sentences

With a super-fight now in Price's sights, her promoter Ben Shalom said the Welshwoman could be the number one pound-for-pound female fighter on the planet by the end of the year.

From BBC • Apr. 4, 2026

Both El Niño and its counterpart La Niña are natural shifts in global weather patterns, primarily focused on Pacific Ocean temperatures, but they can impact the whole planet.

From Salon • Apr. 4, 2026

They relied on a computer algorithm to detect tiny, repeated dips in starlight that occur when a planet passes in front of its star.

From Science Daily • Apr. 4, 2026

"Enceladus itself is a key driver of this environment, releasing huge amounts of water vapor that gets ionized, loading the magnetosphere with heavy plasma that is then pulled around as the planet spins."

From Science Daily • Apr. 3, 2026

“By reducing its half-life, you will be able to occupy the planet far sooner,” I go on, hoping she won’t be able to resist.

From "The Last Cuentista" by Donna Barba Higuera

Related Words

• asteroid
• earth
• globe
• sphere
• world