psy·che·del·ic / ˌsīkəˈdelik/ • adj. relating to or denoting drugs (esp. LSD) that produce hallucinations and apparent expansion of consciousness. ∎  relating to or denoting a style of rock music originating in the mid-1960s, characterized by musical experimentation and drug-related lyrics. ∎  denoting or having an intense, vivid color or a swirling abstract pattern: a psychedelic T-shirt.• n. a psychedelic drug.DERIVATIVES: psy·che·del·i·cal·ly / -ik(ə)lē/ adv.

psychedelic (sy-ki-del-ik) adj. describing drugs, such as cannabis and LSD, that can induce changes in the level of consciousness of the mind.