[In some way from Gr. λήθη (see LETHE); perh. meant for Gr. ληθαῖον, neut. of ληθαῖος LETHEAN a.] Sulphuric ether when used as an anæsthetic (see quot. 1880).
1847. N. Brit. Rev., VII. 173. The discoverer of what has been termed ‘the Letheon’—or, at least, of the system of ‘Letheonizing.’ Ibid., 205. A convict lately … has begged to be executed while under the Letheon’s influence.
1880. Libr. Univ. Knowl. (N. Y.), X. 241. Dr. [W. T. G.] Morton [of Boston] obtained a patent for the use of ether [as an anæsthetic], under the name of ‘letheon,’ in 1846.
Hence Letheonize v., trans. to subject to the action of letheon.
1847. N. Brit. Rev., VII. 178. A Mr. H. Wells … dentist, is announced as having practised letheonizing since October 1844.
