What is the meaning of astronaut?

The Greeks had two words for ‘star’, astēr and astron. They go back to an ancient root that is also the source of the Latin word stella, which gave us itself and also stellar (mid 17th century). An asterisk is a little star, the meaning of its source, Greek asteriskos. Asteriskos is from astēr, which is also the root of asteroeidēs, ‘star-like’. This entered English in the early 19th century as asteroid (early 19th century), a term coined by the astronomer William Herschel. astēr also gave us our name for the plant aster (early 18th century), which has petals rather like an asterisk. Words beginning with astro- come from astron. In the Middle Ages astronomy (Middle English) covered not only astronomy but astrology too. The Greek word it descends from meant ‘star-arranging’. Rather poetically, an astronaut [1920s] is literally a ‘star sailor’. The word comes from Greek astron ‘star’ and nautēs ‘sailor’. It was modelled on aeronaut (late 18th century), a word for a traveller in a hot-air balloon or airship. Cosmonaut [1950s], the Russian equivalent of astronaut, literally means ‘sailor in the cosmos’.