Etymology: < ancient Greek ναύτης sailor (also -ναύτης, combining form, in e.g. στρογγυλοναύτης merchant seaman; < ναῦς ship (see nave n.2) + -της, suffix forming agent nouns), after Argonaut n. and mesonaut n. Compare Middle French, French -naute (in e.g. argonaute, late 15th cent.; earliest in a native formation in aéronaute, late 18th cent.).The earliest loanwords with this element are Argonaut n. (16th cent.) and mesonaut n. (17th cent.), which probably contributed towards the adoption of aeronaut n. from French aéronaute and the formation of the humorous airgonaut n. (both late 18th cent.). On this model were formed astronaut n. and aquanaut n. (both late 19th cent.) and 20th-cent. formations such as cosmonaut n., lunarnaut n., and oceanaut n. Recent formations have tended towards the figurative, as responaut n. and cybernaut n.
This is a new entry (OED Third Edition, June 2003; most recently modified version published online March 2019).