planet

noun

plan·​et ˈpla-nət 

1

a(1)

: any of the large bodies that revolve around the sun in the solar system

(2)

: a similar body associated with another star

b

: earth

—usually used with the

one of the hottest places on the planet

c

: 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

2

: a celestial body held to influence the fate of human beings

3

: a person or thing of great importance : luminary

planetlike

ˈpla-nət-ˌlīk 

adjective

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 word 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 line with astronomical discovery and advancement, planet began to be used specifically of the rocky or gaseous bodies that orbit around the sun—a definition which excluded the moon and 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.

Synonyms

• globe
• world
• earth

Examples of planet in a Sentence

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

Recent Examples on the Web

The film follows a mission to colonize a distant planet, and takes place on a spaceship populated by an army of young people who will give birth to the generation that will ultimately do the colonizing. —Bilge Ebiri, Vulture, 30 Oct. 2025

Made almost entirely of water ice, the rings extend out in a startlingly flat plane perpendicular to the planet’s orbital axis. —Tom Hawking, Popular Science, 30 Oct. 2025

The continent is home to 60% of the planet’s uncultivated arable land that is capable of sequestering immense amounts of carbon—yet only 16% of the global carbon credits market. —Charlie Campbell, Time, 30 Oct. 2025

Both parties are trying to broaden consumers’ choices for sustainable fashion without compromising affordability, quality or the planet. —Rosemary Feitelberg, Footwear News, 30 Oct. 2025

Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing planet

• inferior planet
• inner planet
• minor planet
• outer planet
• planet-stricken
• planet-struck
• planet wheel
• preserve the planet
• superior planet

Rhymes for planet

• gannet
• granite
• intranet
• pomegranate

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Kids Definition

planet

noun

plan·​et ˈplan-ət 

: a heavenly body other than a comet, asteroid, or satellite that travels in orbit around the sun

also : such a body orbiting another star

Etymology

Middle English planete "planet," from early French planet (same meaning), from Latin planeta (same meaning), from Greek planēt-, planēs "planet," literally, "wanderer"

Word Origin

Most of the stars seem to have fixed positions when they are compared to other stars. There are some heavenly bodies, however, that clearly change their positions in relation to the stars and to each other. They seem to wander about among the fixed stars. The ancient Greek name for such a heavenly body was planēs, which means "wanderer." The English word planet comes from the Greek planēs. Unlike the ancient Greeks, we now know that the planets "wander" across the sky because they are revolving around the sun.