1) can refer to an actual hallucinogen, the substance itself. Acid, mushrooms, peyote, mescaline, and numerous research chemicals qualify
2)more often used to describe art produced by visions after ingesting psychedelic drugs. This art may be visual, musical, comedy, acting in movies, cartoons, and other forms dedicated to the psychedelic experience a person has under the influence
Psychedelic art and music has been prevalent since the 60s in counter culture. Especially in the 60s and 70s. However, psychedelic art has really been around much longer in tribal forms, and is still prevalent today in movies, music, and other art.
By Solid Mantis