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

Unlike semaglutide, the active ingredient in Ozempic and Wegovy, BRP is not a GLP-1 agonist. —Allison Palmer, Miami Herald, 11 June 2026

Retatrutide is a triple agonist, adding glucagon for a metabolism boost. —Alexa Lomonaco, CNBC, 8 June 2026

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

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