Encyclopædia Britannica, Ninth Edition/Anodyne

ANODYNE (α privative, and ὀδύνη, pain), denotes etymologically anything which relieves pain. The common usage of the word restricts it, however, to medicines which lessen the sensibility of the brain or nervous system, without acting directly on the cause of pain. The anodynes generally employed are opium, henbane, hemlock, tobacco, stramonium, and chloroform.