agonist

American  

[ag-uh-nist] / ˈæg ə nɪst /

noun

1. a person engaged in a contest, conflict, struggle, etc., especially the protagonist in a literary work.

2. a person who is torn by inner conflict.

3. Physiology. a contracting muscle whose action is opposed by another muscle.

4. Pharmacology. a chemical substance capable of activating a receptor to induce a full or partial pharmacological response.

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agonist British  

/ ˈæɡənɪst /

noun

1. any muscle that is opposed in action by another muscle Compare antagonist

2. a competitor, as in an agon

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agonist Scientific  

/ ăg′ə-nĭst /

1. A muscle that actively contracts to produce a desired movement.

2. A chemical substance, especially a drug, that can combine with a receptor on a cell to produce a physiologic response.

3. Compare antagonist

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Etymology

Origin of agonist

First recorded in 1620–30; from Late Latin agōnista, from Greek agōnistḗs “contestant,” equivalent to agṓn agon + -istēs -ist

Example Sentences

There are even differences in how people respond to the different drugs, because Wegovy is a GLP-1 receptor agonist, and Zepbound is a GLP-1/GIP agonist.

From MarketWatch • May 18, 2026

INBRX-106 is an OX40 agonist, a type of immunotherapy many pharmaceutical companies have unsuccessfully tried to develop.

From Barron's • May 11, 2026

If a patient’s body is already producing GLP-1 at normal or elevated levels, prescribing a long-acting agonist isn’t correcting a deficit; it may be amplifying a signal that’s already there.

From Slate • Mar. 22, 2026

The team redesigned a CD40 agonist antibody to improve its effectiveness while reducing harmful side effects.

From Science Daily • Mar. 16, 2026

Reproach she looks, about, above, Denied her light, denied her love, Denied for what she sacrificed, Doomed to be fruitless agonist.

From Helen Redeemed and Other Poems by Hewlett, Maurice Henry