oneironaut in English dictionary oneironaut Meanings and definitions of "oneironaut" A person who explores dream worlds, usually associated with lucid dreaming. noun A person who explores dream worlds, usually associated with lucid dreaming. more Grammar and declension of oneironaut oneironaut ( plural oneironauts) oneironaut (plural oneironauts) more Sample sentences with "oneironaut" Declension Stem Try again Available translations Finnish French Portuguese Serbo Croatian Authors