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 of planet

• 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

In our own solar system, giant planets such as Jupiter and Saturn are thought to have begun rapidly accumulating their massive gaseous envelopes once their growing cores reached roughly 20 times Earth's mass. — Samantha Mathewson, Space.com, 19 Aug. 2026

Long after all humans have vanished from our planet, some extragalactic visitors might land gently on an empty seashore, throw a bucket into the sea and haul up samples of bacteria. — Aaron Shattuck, Scientific American, 18 Aug. 2026

In the early days, utopias were generally located on our own planet, in places as yet undiscovered, or which were so far away that anything was possible. — Carline Tromp, The Dial, 18 Aug. 2026

Observing the constellations, the faint glow of distant planets, and the occasional shooting star left me with a sense of awe. — Jen Murphy, Condé Nast Traveler, 18 Aug. 2026

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.