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

Orforglipron is a small-molecule, oral glucagon-like peptide-1 (GLP-1) receptor agonist. —Hannah Millington, MSNBC Newsweek, 17 Sep. 2025

If lifestyle changes aren’t enough, your doctor may consider things like glucagon-like peptide-1 agonists such as Ozempic, Wegovy, Mounjaro or Zepbound. —Bruce Y. Lee, Forbes.com, 16 Sep. 2025

Seeking to make a better STING agonist, researchers at the University of Cambridge came up with an elegant solution. —New Atlas, 16 Sep. 2025

How GLP-1s work GLP-1 receptor agonists work by mimicking a hormone called glucagon-like peptide-1, which is released from the gut after eating. —Melissa Rudy, FOXNews.com, 10 Sep. 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