In many English-speaking nations, the term astronaut is used for a (professional) space traveler. The term derives from the Greek words ástron for "star" and nautes (ναύτης), for "sailor". The first known use of the term "astronaut" in the modern sense was by Neil R. Jones in his short story The Death's Head Meteor in 1930.

Space travelers employed by the Russian Federal Space Agency are called a cosmonaut in English texts derived from the Greek kosmos (κόσμος) for "universe".