: a substance and especially a drug that induces hallucinations
Substance that produces psychological effects normally associated only with dreams, schizophrenia, or religious visions. It produces changes in perception (ranging from distortions in what is sensed to perceptions of objects where there are none), thought, and feeling. Those that have aroused the most controversy include Ecstasy, LSD, mescaline, psilocybin (from certain mushrooms), and bufotenine (from the skin of toads); some would add marijuana. The mode of action is still not clear; serotonin, epinephrine, or other neurotransmitters may be affected.