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

In recent years, a class of drugs known as GLP-1 agonists have become wildly popular for patients seeking to lose weight. —Fortesa Latifi, Rolling Stone, 9 Aug. 2025

Medications known as glucagon-like peptide-1 agonists, or GLP-1s, have become very popular as weight loss agents. —Joshua P. Cohen, Forbes.com, 7 Aug. 2025

Glucagon-like peptide-1 receptor agonist eligibility among US adolescents and young adults. —Hannah Millington, MSNBC Newsweek, 4 Aug. 2025

While the development and proliferation of the GLP-1 receptor agonist class of drugs has dominated headlines for several years, SANA is nothing like Ozempic. —New Atlas, 23 July 2025

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