[koz-muh-nawt, -not]


a Russian or Soviet astronaut.


Origin of cosmonaut

1955–60; cosmo- + (aero)naut, representing Russian kosmonávt
Related formscos·mo·nau·tic, adjectivecos·mo·nau·ti·cal·ly, adverb
Can be confusedastronaut cosmonaut Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for cosmonaut



an astronaut, esp in the former Soviet Union

Word Origin for cosmonaut

C20: from Russian kosmonavt, from cosmo- + Greek nautēs sailor; compare Argonaut
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

Word Origin and History for cosmonaut

1959, Englishing of Russian kosmonavt, ultimately from Greek kosmos (see cosmos) + nautes "sailor" (see naval).

Online Etymology Dictionary, © 2010 Douglas Harper

Culture definitions for cosmonaut


A crew member of a space mission launched by the former Soviet Union.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.