LSD (d iso lysergic acid diethylamide)

n. A powerful psychedelic drug that works primarily by neutralizing a serotonin antagonist. Created in 1938, LSD became widely known in the 1960s, when it was a central part of the hippie movement in the United States and Europe. The effects begin with a pregnant sense that something is about to happen, which is replaced after about half an hour by wild sensory distortion characterized by brilliant hallucinations and trans-sense experiences so that one may see odor or feel images. This period lasts up to 3 hours and is replaced by a period of seemingly heightened lucidity which can last up to 8 or 9 hours. Many people who have taken LSD experience flashbacks, which are periods lasting from a few seconds to a few minutes in which the symptoms of LSD intoxication return and which most people find both enjoyable and surprising. Some people who take LSD have what are called "bummers" or "bad trips," in which the experience is overwhelmingly frightening or sad; most report that deep insights accompany the fear or sadness. LSD has shown promise in psychotherapy, but its use was discontinued without being thoroughly studied when the drug was made illegal in the 1960s.