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

• earth
• globe
• world

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 pope touched on a series of woes wreaking havoc on the planet: polluted air, water poverty, toxic waste, industrial pollution, rising sea levels and extreme weather. —Rachel Ramirez, CNN Money, 27 Apr. 2025

Mercury, the last of the easily visible planets, may also be visible almost directly on the horizon. —Anthony Wood, Space.com, 26 Apr. 2025

Musk has never denied his hard-charging style and believes that his work building electric cars and rockets is crucial for the health of the planet and the continuation of the human species, and that his DOGE work responds to threats of U.S. bankruptcy. —Jonathan Landay, USA Today, 26 Apr. 2025

This is, of course, where most of the population of the planet lives as well. —Eric MacK, Forbes.com, 25 Apr. 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.