Is it ensure, insure, or assure?
1843, short for neuro-hypnotism (1842), coined by Dr. James Braid of Manchester, England, from hypnotic + -ism. In the same work (1843) Braid coined the verb hypnotize.
hypnotism hyp·no·tism (hĭp'nə-tĭz'əm)n.
The theory or practice of inducing hypnosis.
The act of inducing hypnosis.