Definition from Nolo’s Plain-English Law Dictionary
Drugs that dull the senses or alter perception. Popularly used to describe drugs that cannot be legally possessed, sold, or transported except for medicinal uses for which a physician or dentist's prescription is required. Among these "controlled substances" are heroin, cocaine, L.S.D., opium, methamphetamine ("speed"), angel dust, hashish, and numereous chemically-designed hallucinagenics, as well as drugs with a legitimate medical use such as morphine. Dealing in any of these narcotics is a felony (subject to a prison term) under both state and federal laws, although mere use may be a misdemeanor. Marijuana is also an illicit narcotic, but possession of small amounts for personal use is a misdemeanor in most states.