A hallucinogen is a type of drug that alters the user's perception, thoughts, and feelings. PEYOTE (6 letters) is a hallucinogenic cactus native to Mexico and the southwestern United States. It has been used for centuries by Native Americans in religious ceremonies. LSD (3 letters) is a synthetic hallucinogen that was first synthesized in 1938. It is known for its powerful effects on the mind and is often used recreationally.