The word psychedelic is an English term coined from the Greek words for "soul," ψυχή (psyche), and "manifest," δήλος (delos). A psychedelic experience is characterized by the perception of aspects of one's mind previously unknown, or by the creative exuberance of the mind liberated from its ostensibly ordinary fetters. Psychedelic states are an array of experiences elicited by sensory deprivation as well as by psychedelic substances. Such experiences include hallucinations, changes of perception, synesthesia, altered states of awareness, mystical states, and occasionally states resembling psychosis.
The term was first coined as a noun in 1957 by psychiatrist Humphry Osmond as an alternative descriptor for hallucinogenic drugs in the context of psychedelic psychotherapy. Timothy Leary, who was largely responsible for the popularization of the term "psychedelic", was a well-known proponent of their use, as was Aldous Huxley. Both, however, advanced widely different opinions on the broad use of psychedelics by state and civil society. Leary promulgated the idea of such substances as a panacea, while Huxley suggested that only the cultural and intellectual elite should partake of entheogens systematically.
The use of psychedelic drugs became widespread in the modern West in the mid-1960s. One of the first uses of the word in the music scene of this time was in the 1964 recording of "Hesitation Blues" by the Holy Modal Rounders. The term was introduced to rock music and popularized by the 13th Floor Elevators 1966 album The Psychedelic Sounds of the 13th Floor Elevators.
The counterculture of the 1960s had a strong influence on the popular culture of the early 1970s, and is well recognized even by those who are naïve to its psychedelic origins. It later became linked to a style of electronic dance music commonly known as psychedelic trance.
At the same time as psychedelic drugs were being used by the counterculture of the 1960s, they were also being used in experiments by governments, who saw them and sensory deprivation as useful agents for mind control; see MKULTRA for the CIA involvement in the use of psychedelic drugs.