I. ˌsī-kə-ˈde-lik noun
Etymology: irregular from psych- + Greek dēloun to show, from dēlos evident; akin to Sanskrit dīdeti it shines, Latin dies day — more at deity
Date: 1956
: a psychedelic drug (as LSD)
II. adjective
Date: 1957
1.
a. : of, relating to, or being drugs (as LSD) capable of producing abnormal psychic effects (as hallucinations) and sometimes psychotic states
b. : produced by or associated with the use of psychedelic drugs
a psychedelic experience
2. : imitating, suggestive of, or reproducing effects (as distorted or bizarre images or sounds) resembling those produced by psychedelic drugs
psychedelic color schemes
• psy·che·del·i·cal·ly -ˈde-li-k(ə-)lē adverb