Morphine (INN) (IPA: ) is a highly potent opiate analgesic drug and is the principal active agent in opium and the prototypical opiate. Like other opiates, e.g. diacetylmorphine (heroin), morphine acts directly on the central nervous system (CNS) to relieve pain, and at synapses of the nucleus accumbens in particular. Studies done on the efficacy of various opioids have indicated that, in the management of severe pain, no other narcotic analgesic is more effective or superior to morphine. Morphine is highly addictive when compared to other substances, and tolerance, physical and psychological dependences develop very rapidly.
The word "morphine" is derived from Morpheus, the god of dreams in Greek mythology. He is the son of Hypnos, god of sleep.