Psychedelic derives from two Ancient Greek words, psyche meaning "mind" or "soul," and delos meaning "reveal" or "manifest."

Greek psykhē "mind" + dēloun "make visible, reveal," from dēlos "visible, clear," from PIE root *dyeu- "to shine.

The term “psychedelic” was introduced first time by British psychologist Humphry Osmond (1917 - 2004) who wrote to his friend Aldous Huxley in 1957 seeking a word to use as a reference for hallucinogenic drugs. Huxley responded in verse: “to make this mundane world sublime/Take half a gram of phanerothyme.” His word, “phanerothyme” was a combination of the Greek words for “manifest” (phaneros) and “spirit” (thumos). However, it was Osmond”s reply that stuck: “To fathom Hell or soar angelic/Just take a pinch of psychedelic (a combo of “soul” (psuche) and “to manifest” (deloun).