cos·​mo·​naut ˈkäz-mə-ˌnȯt How to pronounce cosmonaut (audio)
: an astronaut of the Soviet or Russian space program

Examples of cosmonaut in a Sentence

Recent Examples on the Web Left behind aboard the space station were their replacements, Crew 8 commander Matthew Dominick, co-pilot Michael Barratt, Jeanette Epps and cosmonaut Alexander Grebenkin along with Soyuz crewmates Oleg Kononenko, Nikolai Chub and NASA astronaut Loral O'Hara. William Harwood, CBS News, 12 Mar. 2024 The presence of a Russian cosmonaut on the flight is another reminder of the binding partnership between Russia and the United States in space that has continued despite growing tensions between the countries over the war in Ukraine. Christian Davenport, Washington Post, 2 Mar. 2024 Since nothing changed, Russian cosmonauts entered and emptied most of Progress’ cargo for about five days before closing the hatch again. Will Sullivan, Smithsonian Magazine, 1 Mar. 2024 As the cosmonauts sing along, filled with nostalgia and emotion, they are gently ribbed by their American counterparts, a trio of astronauts, but the mood is jovial. Katie Walsh, Los Angeles Times, 19 Jan. 2024 Its four crew members are NASA astronauts Commander Matthew Dominick, Pilot Michael Barratt, Mission Specialist Jeanette Epps and Roscosmos cosmonaut Mission Specialist Alexander Grebenkin. Richard Tribou, Orlando Sentinel, 14 Jan. 2024 The two cosmonauts are midway through a yearlong stay aboard the space station while O'Hara is wrapping up a more typical six-month tour. William Harwood, CBS News, 5 Mar. 2024 They will be welcomed aboard ISS by the seven members of the station’s current regular crew — two Americans from NASA, one astronaut each from Japan and Denmark and three Russian cosmonauts. Reuters, NBC News, 21 Jan. 2024 While aboard the station, the seven astronauts and cosmonauts have been conducting a variety scientific experiments and studying an array of microgravity phenomena. Eric Lagatta, USA TODAY, 16 Jan. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'cosmonaut.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Russian kosmonavt, from Greek kosmos + Russian -navt (as in aeronavt aeronaut)

First Known Use

1955, in the meaning defined above

Time Traveler
The first known use of cosmonaut was in 1955

Dictionary Entries Near cosmonaut

Cite this Entry

“Cosmonaut.” Dictionary, Merriam-Webster, Accessed 19 Apr. 2024.

Kids Definition


cos·​mo·​naut ˈkäz-mə-ˌnȯt How to pronounce cosmonaut (audio)
: a Soviet or Russian astronaut

More from Merriam-Webster on cosmonaut

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!