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

Mid-stage data on petrelintide are due early next year, while data on its dual GLP-1 agonist called survodutide will read out throughout 2026. —Elsa Ohlen, CNBC, 11 Dec. 2025

The experimental medication uses a new form of beta-2 agonist that benefits muscle function while also avoiding overstimulation of the heart, which has been identified as a potential safety concern of older versions. —Melissa Rudy, FOXNews.com, 10 Dec. 2025

Alpha-2 receptor agonists lower the activity of the sympathetic nervous system. —Craig O. Weber, Verywell Health, 4 Dec. 2025

The guidance comes as demand for the class of drugs known as GLP-1 agonists has surged worldwide, and governments are figuring out how to include the blockbuster therapies into public health systems. —Mrinalika Roy, USA Today, 1 Dec. 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