Narcotic

Having the properties of a narcotic; operating as a narcotic.

A drug which, in medicinal doses, generally allays morbid susceptibility, relieves pain, and produces sleep; but which, in poisonous doses, produces stupor, coma, or convulsions, and, when given in sufficient quantity, causes death. The best examples are opium (with morphine), belladonna (with atropine), and conium.

a drug that produces numbness or stupor; often taken for pleasure or to reduce pain; extensive use can lead to addiction