Real Dictionary

narcotic
adjective: If something, especially a drug, has a narcotic effect, it makes the person who uses it feel sleepy.
countable noun: Narcotics are drugs such as opium or heroin which make you sleepy and stop you feeling pain. You can also use narcotics, especially in American English, to mean any kind of illegal drug.

narcotic in American English
a drug, as opium or any of its derivatives (morphine, heroin, codeine, etc.), used to relieve pain and induce sleep: narcotics are often addictive and in excessive doses can cause stupor, coma, or death
of, like, or capable of producing narcosis
adjective: of or having the power to produce narcosis, as a drug
noun: any of a class of substances that blunt the senses, as opium, morphine, belladonna, and alcohol, that in large quantities produce euphoria, stupor, or coma, that when used constantly can cause habituation or addiction, and that are used in medicine to rel

narcotic in British English
adjective: of, relating to, or designating narcotics
noun: any of a group of drugs, such as heroin, morphine, and pethidine, that produce numbness and stupor. They are used medicinally to relieve pain but are sometimes also taken for their pleasant effects; prolonged use may cause addiction

narcotic in the Pharmaceutical Industry 1
noun: A narcotic is any of a group of drugs, such as heroin, morphine, and pethidine, that produce numbness and near-unconsciousness. Narcotics are used medicinally to relieve pain.

narcotic in the Pharmaceutical Industry 2
adjective: A narcotic drug relieves pain or induces numbness or sleepiness.