Named after Hypnos, Greek god of sleep — coiner James Braid later regretted it, since hypnosis isn't actually sleep.
An artificially induced state of relaxation and concentration in which a person is more responsive to suggestion.
From Greek 'Hypnos' (Ὕπνος), the personification and god of sleep in Greek mythology, + '-osis' (condition, process). The term 'hypnotism' was coined by Scottish surgeon James Braid in 1843, replacing 'mesmerism' (named for Franz Mesmer's now-discredited theory of 'animal magnetism'). Hypnos was the twin brother of Thanatos (Death) and the son of Nyx (Night), and he lived in a cave through which the river Lethe (Forgetfulness) flowed — a mythological geography that perfectly
James Braid coined 'hypnotism' from Hypnos, the Greek god of sleep, but almost immediately regretted the name because he realized hypnosis was not actually sleep. He tried to rename it 'monoideism' (fixation on one idea), but the original term had already caught on and could not be dislodged.