planet definition | Dictionary.com

Synonyms of planet

earth, globe, heavenly body, world, apple, marble, orb, sphere,

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8 dictionary results for: planet

Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

plan⋅et

[plan-it]

–noun

Astronomy.

a.	Also called major planet. any of the nine large heavenly bodies revolving about the sun and shining by reflected light: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto in the order of their proximity to the sun.

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

c.	(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.

Origin:
1250–1300; ME planete (< OF planète) < LL planēta, planētēs (found only in pl. planētae) < Gk (astéres) plan

tai lit., wandering (stars)

Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.
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American Heritage Dictionary - Cite This Source - Share This

plan·et (plān'ĭt) Pronunciation Key

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n.

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.
One of the seven celestial bodies, Mercury, Venus, the moon, the sun, Mars, Jupiter, and Saturn, visible to the naked eye and thought by ancient astronomers to revolve in the heavens about a fixed Earth and among fixed stars.
One of the seven revolving astrological celestial bodies that in conjunction with the stars are believed to influence human affairs and personalities.

[Middle English, from Old French planete, from Late Latin planēta, from Greek planētēs, variant of planēs, planēt-, from planāsthai, to wander; see pelə-² in Indo-European roots.]

Usage Note: Clyde Tombaugh's discovery of Pluto in 1930 added a ninth planet to our solar system, and thereafter students of astronomy were taught the familiar list of nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. But in 2006, the International Astronomical Union (IAU) voted to change the definition of planet, requiring that a clestial body must have enough mass to assume a round shape and "clear the neighborhood around its orbit" in order to qualify as a planet. This means that a planet cannot have other objects in or crossing its orbit except smaller objects that have been captured by its gravity, such as those that revolve around it as moons. Because Neptune's large mass has captured Pluto so that the two planets remain in orbits that cross, Pluto has not cleared its own orbit and was therefore demoted from planet status to that of a newly created category, dwarf planet. Like a planet, a dwarf planet orbits the sun, is large enough to assume a nearly round shape, and does not orbit a planet (as our Moon does). But a dwarf planet does not clear the neighborhood around its orbit and may cross the paths of other objects orbiting the sun. Other dwarf planets include Ceres, whose orbit is in the asteroid belt betwen Mars and Jupiter, and Eris, an object in the Kuiper belt beyond Pluto. At the same meeting the IAU created a third category of objects known as small solar system bodies, which includes asteroids (sometimes referred to as "minor planets," compounding the difficulty of the term planet,) comets, objects beyond Netpune's orbit, and other nonspherical bodies. Although officially approved, this new scheme of the solar system remains controversial among astronomers and may well be revised.

The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2006 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Online Etymology Dictionary - Cite This Source - Share This
planet

late O.E., from O.Fr. planete (Fr. planète), from L.L. planeta, from Gk. (asteres) planetai "wandering (stars)," from planasthai "to wander," of unknown origin. So called because they have apparent motion, unlike the "fixed" stars. Originally including also the moon and sun; modern scientific sense of "world that orbits a star" is from 1640.

Online Etymology Dictionary, © 2001 Douglas Harper
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WordNet - Cite This Source - Share This

planet
noun
1.	(astronomy) any of the nine large celestial bodies in the solar system that revolve around the sun and shine by reflected light; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto in order of their proximity to the sun; viewed from the constellation Hercules, all the planets rotate around the sun in a counterclockwise direction
2.	a person who follows or serves another [syn: satellite]
3.	any celestial body (other than comets or satellites) that revolves around a star

WordNet® 3.0, © 2006 by Princeton University.
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The American Heritage Science Dictionary - Cite This Source - Share This

planet (plān'ĭt) Pronunciation Key

A large celestial body, smaller than a star but larger than an asteroid, that does not produce its own light but is illuminated by light from the star around which it revolves. In our solar system there are nine known planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Because of Pluto's small size—about two-thirds the diameter of Earth's moon—and its unusual orbit, many astronomers believe it should actually be classed as a Kuiper belt object rather than a planet. A planetlike body with more than about ten times the mass of Jupiter would be considered a brown dwarf rather than a planet. See also extrasolar planet , inner planet , outer planet.

planetary adjective

American Heritage New Dictionary of Cultural Literacy, Third Edition - Cite This Source - Share This
planet

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 gases and liquids.

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

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

Free On-line Dictionary of Computing - Cite This Source - Share This

Planet
["An Experiment in Language Design for Distributed Systems", D. Crookes et al, Soft Prac & Exp 14(10):957-971 (Oct 1984)].

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Planet

Plan"et\, n. [OE. planete, F. plan[`e]te, L. planeta, fr. Gr. ?, and ? a planet; prop. wandering, fr. ? to wander, fr. ? a wandering.]

1. (Astron.) A celestial body which revolves about the sun in an orbit of a moderate degree of eccentricity. It is distinguished from a comet by the absence of a coma, and by having a less eccentric orbit. See Solar system.

Note: The term planet was first used to distinguish those stars which have an apparent motion through the constellations from the fixed stars, which retain their relative places unchanged. The inferior planets are Mercury and Venus, which are nearer to the sun than is the earth; the superior planets are Mars, the asteroids, Jupiter, Saturn, Uranus, and Neptune, which are farther from the sun than is the earth. Primary planets are those which revolve about the sun; secondary planets, or moons, are those which revolve around the primary planets as satellites, and at the same time revolve with them about the sun.

2. A star, as influencing the fate of a men.

There's some ill planet reigns. --Shak.

Planet gear. (Mach.) See Epicyclic train, under Epicyclic.

Planet wheel, a gear wheel which revolves around the wheel with which it meshes, in an epicyclic train.