/ ˌsaɪkəˈdelɪk; NAmE / adjective [ usually before noun ]
1.
( of drugs ) causing the user to see and hear things that are not there or that do not exist (= to hallucinate )
2.
( of art, music, clothes, etc. ) having bright colours, strange sounds, etc. like those that are experienced when taking psychedelic drugs
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WORD ORIGIN
1950s: formed irregularly from psyche + Greek dēlos clear, manifest + -ic .