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Synonyms

planetary

American  
[plan-i-ter-ee] / ˈplæn ɪˌtɛr i /

adjective

  1. of, relating to, or resembling a planet or the planets.

  2. wandering; erratic.

  3. terrestrial; global.

  4. Machinery. noting or pertaining to an epicyclic gear train in which a sun gear is linked to one or more planet gears also engaging with an encircling ring gear.

noun

  1. Machinery. a planetary gear train.

planetary British  
/ ˈplænɪtərɪ, -trɪ /

adjective

  1. of or relating to a planet

  2. mundane; terrestrial

  3. wandering or erratic

  4. astrology under the influence of one of the planets

  5. (of a gear, esp an epicyclic gear) having an axis that rotates around that of another gear

  6. (of an electron) having an orbit around the nucleus of an atom

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. a train of planetary gears

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

  • nonplanetary adjective

Etymology

Origin of planetary

From the Latin word planētārius, dating back to 1585–95. See planet, -ary

Explanation

The adjective planetary has to do with any astronomical body that revolves around a star — including the earth. Rather than a circle, planetary motion takes us in an elliptical shape around the sun. In science, planetary usually describes the attributes or motion of planets. It's also used for anything that behaves in a similar way, like planetary electrons, which revolve around their atomic nucleus as if they were tiny planets. You can also talk about things that affect our entire planet using this word: "She worries a lot about the planetary effects of climate change."

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Vocabulary lists containing planetary

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-ary

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The Kent Kresa Space Gallery will feature a wide array of spacecraft, planetary probes, telescopes and more.

From Los Angeles Times • Apr. 13, 2026

"In summary, these results suggest a very carbon-rich, oxygen-poor planetary atmosphere."

From Science Daily • Apr. 6, 2026

The Moon will appear to the astronauts "about the size of a basketball held at arm's length," Noah Petro, head of NASA's planetary geology lab, told AFP.

From Barron's • Apr. 5, 2026

He said: "Micrometeorites are samples of the Solar System's building blocks which can offer insights into early planetary formation, Earth's atmospheric history, and climate evolution."

From BBC • Apr. 4, 2026

An emerging technical civilization, after exploring its home planetary system and developing interstellar spaceflight, would slowly and tentatively begin exploring the nearby stars.

From "Cosmos" by Carl Sagan

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.