agonist

noun

ag·​o·​nist ˈa-gə-nist 

1

: one that is engaged in a struggle

2

[from antagonist]

a

: a muscle that is controlled by the action of an antagonist with which it is paired

b

: a chemical substance capable of combining with a specific receptor on a cell and initiating the same reaction or activity typically produced by the binding endogenous substance

dopaminergic agonists

compare antagonist sense 2b

Examples of agonist in a Sentence

Recent Examples on the Web

One patient who has obesity, PCOS and who lost dozens of pounds on a dual GIP/GLP-1 agonist cannot even get coverage of older anti-obesity medications because her BMI is now normal. —Karen R. Studer, Sacbee.com, 1 June 2026

The research found that patients who began taking GLP-1 receptor agonist drugs after their cancer diagnosis had a lower risk of their cancer progressing, compared with patients taking a different type of medication used to treat diabetes called gliptins. —Victoria Forster, Forbes.com, 25 May 2026

Similar to how GLP-1s (glucagon-like peptide-1 agonists) suppress appetite and trigger weight loss, peptides can signal other functions, like the release of growth hormones. —Angelica Stabile, FOXNews.com, 1 May 2026

This class of medication—known as beta-3 agonists—represents a newer approach to treatment. —Lauryn Higgins, Flow Space, 1 May 2026

Word History

Etymology

borrowed from Late Latin agōnista, borrowed from Greek agōnistḗs, from agōnízesthai "to contend, fight" + -istēs -ist entry 1 — more at agonize

First Known Use

1658, in the meaning defined at sense 1

Rhymes for agonist

• antagonist
• protagonist

Medical Definition

agonist

noun

ag·​o·​nist ˈag-ə-nəst 

1

: a muscle that on contracting is automatically checked and controlled by the opposing simultaneous contraction of another muscle

called also agonist muscle, prime mover

compare antagonist sense a, synergist sense 2

2

: a chemical substance (as a drug) capable of combining with a receptor on a cell and initiating the same reaction or activity typically produced by the binding of an endogenous substance

binding of adrenergic agonists

compare antagonist sense b