What does astronaut mean?
An astronaut is a person trained to travel into outer space aboard a spacecraft, performing tasks that range from operating complex systems to conducting scientific experiments. The word carries strong connotations of courage, discipline, and technical excellence, since becoming an astronaut typically demands years of training in engineering, piloting, survival skills, and physical fitness. In everyday usage it appears in contexts such as 'she trained as an astronaut' or 'the crew included three astronauts', and its figurative reach is modest — it occasionally describes anyone venturing into unknown territory, though such uses are informal. English distinguishes related terms by national program: Russian-trained space travellers are called cosmonauts and Chinese ones taikonauts, but astronaut remains the standard international term. The word derives from the Greek roots astron (star) and nautes (sailor), literally meaning 'star sailor' — a poetic coinage that captures both the romance and the rigour of human spaceflight. It remains one of the most admired professions in popular imagination, symbolising humanity's drive to explore beyond Earth.
nounA person trained to travel and perform duties aboard a spacecraft.
- A person who is trained to travel in a spacecraft, especially as a profession.
"The astronaut spent six months aboard the space station conducting experiments in microgravity."
"She dreamed of becoming an astronaut from the moment she watched the Moon landing on television."
"The astronauts floated weightlessly through the cabin as they prepared their meals."
Regular plural; standard in all contexts.
"Four astronauts were selected for the upcoming lunar mission."
Every astronaut's job description once included the phrase 'survival under extreme conditions' — because for decades, roughly one in fifty people who flew to space died trying.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of astronaut
The word astronaut comes from the ancient Greek roots astron, meaning 'star', and nautes, meaning 'sailor', so it literally means 'star sailor'. The compound was formed in modern times, entering English usage in the early twentieth century before human spaceflight became reality. It shares these Greek roots with words like astronomy and astrology (both built on astron), and with nautical terms derived from nautes-related forms. The parallel term cosmonaut substitutes the Greek-derived kosmos for astron and was adopted for Soviet and later Russian space travellers.
How astronaut is actually used
Neutral register; used internationally. 'Cosmonaut' denotes Russian-trained space travellers and 'taikonaut' Chinese ones, but 'astronaut' is the standard English term for the profession regardless of nationality.
Easily confused with astronaut
An astronaut is the general term for a spacecraft crew member, while cosmonaut specifically refers to one trained by the Russian or former Soviet space program.