opioid

American  

[oh-pee-oid] / ˈoʊ piˌɔɪd /

noun

Biochemistry, Pharmacology.

1. 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.

2. any opiumlike substance.

   Have any opioids been detected in poppies that do not contain opium?

3. any of a group of natural substances, as the endorphins, produced by the body in increased amounts in response to stress and pain.

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adjective

1. pertaining to such a substance.

   opioid drugs such as heroin and oxycodone;

   opioid neuropeptides.

opioid British  

/ ˈəʊpɪˌɔɪd /

noun

1. 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

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Etymology

Origin of opioid

First recorded in 1955–60; opi(um) + -oid

Example Sentences

The increase signals a rebound from declines in life expectancy during the pandemic and progress in combating the opioid crisis, though the U.S. still lags behind peer nations.

From The Wall Street Journal • Feb. 6, 2026

Kaufmann stepped down after steering the company through an onslaught of litigation related to the opioid crisis.

From Barron's • Feb. 5, 2026

Since the ’70s, many other studies have confirmed that placebos can activate opioid receptors, as well as dopamine receptors, which are part of the body’s internal reward system.

From Slate • Jan. 30, 2026

Her lab has played a key role in revealing how selective signaling at opioid receptors can reduce pain without causing breathing suppression or tolerance.

From Science Daily • Jan. 6, 2026

When she wakes up, she will regain consciousness more quickly and clearly because she required lower doses of anaesthetic drugs such as propofol and opioid painkillers than patients who heard no music.

From BBC • Nov. 24, 2025