'aquanaut' originates from English coinage, combining the Latin word 'aqua' (where 'aqua' meant 'water') and the Greek word 'nautēs' (where 'nautēs' meant 'sailor').

'aquanaut' was formed in the 20th century by analogy with words like 'astronaut' and 'aeronaut', combining Latin 'aqua' and Greek 'nautēs' and eventually becoming the modern English word 'aquanaut'.

Initially it referred broadly to a 'water sailor' or person who travels underwater; over time it came to refer more specifically to trained divers who live and work in underwater habitats or perform extended underwater missions.