Psychedelic art is art that has been influenced by psychedelic experiences - hallucinations and apparent expansion of consciousness after ingesting psychoactive drugs. The word "psychedelic" was coined by Humphry Osmond - a British Psychologist. It comes from the word "Psychedelos" meaning open the spirit. Psychedelic in simpler terms translates to "mind manifesting".
According to this definition, all artwork to depict the inner world of the psyche and imagination falls under the category of "psychedelic". "Psychedelic art" also refers to the art movement of the late 1960s counterculture ( Counterculture is a subculture with values very different from the generic & mainstream society, many time in opposition to mainstream cultural notions).
Psychedelic visual arts were a counterpart to psychedelic rock music and is now many times associated with the modern electronic music. They are often associated with multitude of colors and derives heavily from tribal, surrealism and optical illusions.
Psychedelic art, over the years has become an intricate part of festivals, graphic designs, background art, street art and architecture.