interplanetary

adjective

in·​ter·​plan·​e·​tary ˌin-tər-ˈpla-nə-ˌter-ē How to pronounce interplanetary (audio)
: existing, carried on, or operating between planets
interplanetary dust
an interplanetary flight
interplanetary spacecraft

Examples of interplanetary in a Sentence

Recent Examples on the Web
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The company would also deal with the problem of sealing the sample return capsule and making sure that it is decontaminated in accordance with NASA and international safety protocols against interplanetary contamination. New Atlas, 6 July 2025 This is one of the reasons why the timeline and cost of NASA’s rockets and spacecraft and interplanetary missions have ballooned. ArsTechnica, 29 June 2025 In another offering, the company facilitates the transportation of memorial capsules to interplanetary space well beyond the moon. Eric Lagatta, USA Today, 27 June 2025 For our current rocketry, these speeds are so low and the interplanetary distances so great that even the fastest, most direct voyages take years (or even decades for destinations in the outer solar system). Phil Plait, Scientific American, 19 June 2025 See All Example Sentences for interplanetary

Word History

First Known Use

1691, in the meaning defined above

Time Traveler
The first known use of interplanetary was in 1691

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Cite this Entry

“Interplanetary.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/interplanetary. Accessed 11 Jul. 2025.

Kids Definition

interplanetary

adjective
in·​ter·​plan·​e·​tary
ˌint-ər-ˈplan-ə-ˌter-ē
: between planets
interplanetary space
interplanetary travel

More from Merriam-Webster on interplanetary

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