astronaut

noun

plural astronauts
: a person whose profession is to travel beyond the earth's atmosphere
NASA on Wednesday introduced the group of astronauts it has chosen for upcoming missions to the moon. The program, called Artemis, aims to send people back to the moon for the first time since the end of NASA's Apollo program in 1972.—Kenneth Chang
broadly : any person who travels beyond the earth's atmosphere
William Shatner, the 90-year-old actor of "Star Trek" fame, endured a 10-minute, rocket-powered ride to the edge of space … . In that moment, at least one thing became certain: Yes, a nonagenarian can be an astronaut. —Jackie Wattles

Examples of astronaut in a Sentence

Recent Examples on the Web
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The findings will help shape future Mars missions, including those by astronauts, said NASA's acting planetary science director Lindsay Hays. — Arkansas Online, 21 Oct. 2026 Those demonstrations will help inform NASA's determination about which lander the agency will choose to carry astronauts to the moon's surface on Artemis IV, targeted for early 2028. — Josh Dinner, Space.com, 21 Oct. 2026 Musk has said SpaceX’s future success hinges on its Starship rocket, slated to carry astronauts to the moon and launch hundreds of thousands of communications satellites and orbiting data centers to power its AI ambitions. — Los Angeles Times, 20 Oct. 2026 The rocket used old Soviet engines built during the era when Apollo astronauts were landing on the Moon. — Eric Berger, ArsTechnica, 20 Oct. 2026 See All Example Sentences for astronaut

Word History

Etymology

astro- + -naut (in aeronaut)

Note: See note at astronautics.

First Known Use

1928, in the meaning defined above

Time Traveler
The first known use of astronaut was in 1928

Browse Nearby Words

Cite this Entry

“Astronaut.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/astronaut. Accessed 27 Oct. 2026.

Kids Definition

astronaut

noun
: a traveler in a spacecraft
astronautic
ˌas-trə-ˈnȯt-ik
adjective
or astronautical
-i-kəl, 
-nät-
Etymology

from astro- "star, heavens" (derived from Greek astron "star") and -naut (derived from Greek nautēs "sailor," from naus "ship") — related to nausea, nautical see Word History at nausea

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