opiates

Definition of opiate

opiate

(OH-pee-ut)
A substance used to treat pain or cause sleep. Opiates are made from opium or have opium in them. Opiates bind to opioid receptors in the central nervous system. Examples of opiates are codeine, heroin, and morphine. An opiate is a type of analgesic agent.

Source: NCI Dictionary of Cancer Terms