APA Dictionary of Psychology

n. any of a group of drugs with hallucinogenic effects and a common basic chemical structure. The prototype is mescaline, an alkaloid first isolated from the peyote cactus in 1896. Mescaline is one of the least potent of the hallucinogens, but potency is increased by adding methyl groups to the basic molecule, thereby creating substituted phenylethylamines. The latter include the amphetamine derivatives DOM, MDA, and MDMA. See also phenylalkylamine.