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[oh-pee-oid] /ˈoʊ piˌɔɪd/
noun, Biochemistry, Pharmacology
any opiumlike substance.
any of a group of natural substances, as the endorphins, produced by the body in increased amounts in response to stress and pain.
any of several synthetic compounds, as methadone, having effects similar to natural opium alkaloids and their derivatives.
pertaining to such a substance.
1955-60; opi(um) + -oid Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for opioids
  • Heroin mimics a group of molecules called endogenous opioids.
  • The reason is almost certainly the effects of endogenous opioids, better known as endorphins.
  • Finally, opioids can be considered, but they are not a cure.
  • Researchers have shown that placebos can activate the body's own painkilling opioids.
  • If they addressed the brain, it might have been with opioids, whose mechanisms were somewhat mysterious.
  • Constipation, drowsiness, and dry mouth are common side effects of opioids.
  • Other types of drugs, including opioids and barbiturates, are sometimes prescribed off-label for migraine treatment.
  • opioids refer to synthetically produced substances that have the same effect as morphine or codeine.
  • opioids such as morphine may have fewer adverse effects, but some doctors avoid them in gallbladder disease.
  • opioids such as morphine may have fewer adverse effects, but some doctors avoid them for gallbladder disease.
British Dictionary definitions for opioids


  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 substances: opioid 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
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Word Origin and History for opioids



1957, from opium + -oid.

Online Etymology Dictionary, © 2010 Douglas Harper
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opioids in Medicine

opioid o·pi·oid (ō'pē-oid')
See opiate. adj.

o'pi·oid' adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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