Definition of psychonaut in US English:

psychonaut

noun

  • A person who takes psychedelic drugs, especially for the purpose of investigating the effects.

Origin

1970s; earliest use found in The Times. From psycho- + -naut, apparently after German Psychonaut.

Pronunciation

psychonaut

/ˈsʌɪkə(ʊ)ənɔːt/