Meaning

adjective producing distorted sensory perceptions and feelings or altered states of awareness or sometimes states resembling psychosis

adjective having the vivid colors and bizarre patterns associated with psychedelic states

adjective (of a mental state) characterized by intense and distorted perceptions and hallucinations and feelings of euphoria or sometimes despair

originFrom Ancient Greek ψυχή (psukhḗ, “mind, soul”) + δῆλος (dêlos, “manifest, visible”) + English -ic (prefix forming adjectives with the sense ‘of or pertaining to’), coined by the English psychiatrist Humphry Osmond (1917–2004) in a 1956 letter to Aldous Huxley.

Etymology from Wiktionary, CC BY-SA 3.0