Opioid

**Semantic type:** Classification|Organic Chemical

**Definition:** A class of synthetic chemicals/drugs similar to opiates (opium derivatives) with analgesic properties. Due to binding to opiate receptors, opioids mimic opiate activity on neurons, various cells (i.e. lymphocytes), pain suppression and other neurobehavioral activity. (NCI)

**Synonyms:** - Narcotic - narcotic - opioid