[ oh-pee-oid ]
/ ˈoʊ piˌɔɪd /

noun Biochemistry, Pharmacology.

an opiate, or any similar synthetic compound: formerly referring only to the latter, but now the predominant term for both the opium-derived and synthetically produced substances: Illicit use of the synthetic opioid fentanyl is on the rise.The opium poppy is the source for all natural opioids.
any opiumlike substance: Have any opioids been detected in poppies that do not contain opium?
any of a group of natural substances, as the endorphins, produced by the body in increased amounts in response to stress and pain.


pertaining to such a substance: opioid drugs such as heroin and oxycodone;opioid neuropeptides.

Origin of opioid

First recorded in1955–60; opi(um) + -oid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for opioid

British Dictionary definitions for opioid

/ (ˈəʊpɪˌɔɪd) /


  1. any of a group of substances that resemble morphine in their physiological or pharmacological effects, esp in their pain-relieving properties
  2. (modifier) of or relating to such substancesopioid receptor; opioid analgesic
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for opioid

[ ōpē-oid′ ]





Other words from opioid

opi•oid′ adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.