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.

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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

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noun

1. a train of planetary gears

Other Word Forms

• nonplanetary
  adjective

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Etymology

Origin of planetary

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

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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."

Example Sentences

See Examples For:

planetary

These immense weather systems can span planetary scales, continually changing the appearance of the distant world.

From Science Daily ● Oct. 17, 2026

That spacecraft became the first successful planetary science mission, marking a major milestone in the exploration of other worlds.

From Science Daily ● Oct. 12, 2026

Supporters argued the project had brought industries together behind a single planetary mission.

From BBC ● Oct. 8, 2026

"Beagle 2 started the UK down the line of being able to do planetary missions and knowing it could engineer them," said Professor Mark Sims, who managed the Beagle 2 mission.

From BBC ● Oct. 5, 2026

I look over at Brian’s house, wishing he were on his roof, wishing he knew how sorry I was, wishing he’d come over and talk about planetary orbits and solar flares.

From "I'll Give You the Sun" by Jandy Nelson

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Related Words

• global
• terrestrial

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