noun plan·et \ ˈpla-nət \
|Updated on: 29 Jul 2018

Definition of planet

1 a : any of the seven celestial bodies sun, moon, Venus, Jupiter, Mars, Mercury, and Saturn that in ancient belief have motions of their own among the fixed stars
b (1) : any of the large bodies that revolve around the sun in the solar system
(2) : a similar body associated with another star
c : earth usually used with the
2 : a celestial body held to influence the fate of human beings
3 : a person or thing of great importance : luminary


play \ˈpla-nət-ˌlīk\ adjective

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Examples of planet in a Sentence

  1. our collective responsibility to conserve the planet and its natural resources for future generations

Recent Examples of planet from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'planet.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Did You Know?

Planet goes back to ancient Greek planēt- (literally, "wanderer"), which is derived from "planasthai," a Greek verb which means "to wander." The name "planet" was originally applied to any of seven visible celestial bodies which appeared to move independently of the fixed stars - the sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. In the 17th century, "planet" began to be used specifically of the rocky or gaseous bodies that orbit around the sun - a definition which excluded the moon and, obviously, the sun, but included the Earth and, as they were discovered, Uranus, Neptune, and Pluto. In 2006, the International Astronomical Union developed a narrower definition of "planet," effectively demoting Pluto to the status of a "dwarf planet," a celestial body that is spherical and orbits the sun but is not large enough to disturb other objects from its orbit.

Origin and Etymology of planet

Middle English planete, from Anglo-French, from Late Latin planeta, modification of Greek planēt-, planēs, literally, wanderer, from planasthai to wander — more at floor

planet Synonyms

PLANET Defined for Kids


noun plan·et \ ˈpla-nət \

Definition of planet for Students

: any large heavenly body that orbits a star (as the sun)

History for planet

Most stars seem to stay in fixed positions night after night. There are certain heavenly bodies, the planets, that look very much like stars but are not. They seem to wander about among the fixed stars. The ancient Greeks gave them the name planētes, meaning “wanderers.” The English word planet comes from this Greek word.

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resembling the blue of the sky

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