hallucinogen

hallucinogen A drug or other chemical substance that causes hallucinations (profound distortions in a person’s perceptions of reality). Under the influence of hallucinogens, people see images, hear sounds, and feel sensations that seem real but do not exist. Some hallucinogens also produce rapid, intense emotional swings. An example of a hallucinogen is lysergic acid diethylamide (LSD).