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See more synonyms for opioid on Thesaurus.com
noun Biochemistry, Pharmacology.
  1. any opiumlike substance.
  2. any of a group of natural substances, as the endorphins, produced by the body in increased amounts in response to stress and pain.
  3. any of several synthetic compounds, as methadone, having effects similar to natural opium alkaloids and their derivatives.
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  1. pertaining to such a substance.
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Origin of opioid

First recorded in 1955–60; opi(um) + -oid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for opioid


    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
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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

Word Origin and History for opioid


1957, from opium + -oid.

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Online Etymology Dictionary, © 2010 Douglas Harper

opioid in Medicine


Related formsopi•oid′ adj.