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

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

The cases are using a similar script to past ones accusing pharmaceutical companies of perpetuating the opioid epidemic or tobacco companies of failing to warn about harm from cigarettes, cases that led to multibillion-dollar settlements.

From The Wall Street Journal • Jan. 26, 2026

Their latest findings were published December 17 in Nature under the title "GTP release-selective agonists prolong opioid analgesic efficacy."

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

The Sacklers have consistently denied wrongdoing over the opioid crisis.

From Barron's • Nov. 14, 2025