(from a privative, and ἄνω, above; or a neg. and ὀνείρον, pain), a term applied to medicines which ease pain, and procure sleep. They are divided into three sorts, viz. 1. Parergotics, or such as afflue pain. 2. Hypnotics, or such as relieve by procuring sleep. 3. Narcotics, or such as ease the patient by stupifying him.

Opiates and narcotics destroy sensation. Some hypnotics and parergotics, as nitre, camphor, &c., procure ease and sleep by removing the offending cause. Camphor is said to be the best anodyne in nervous cases and at the decline of fevers. The doses of these medicines are generally regulated by the pulse.