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

The study follows volunteers taking another Novo Nordisk GLP-1 agonist called liraglutide (sold under the brand names Victoza and Saxenda) for an entire year, with or without the addition of a regular exercise program. —Alex Hutchinson, Outside, 25 Mar. 2026

These medications work like GLP-1 agonists but also target the hormone glucose-dependent insulinotropic polypeptide (GIP). —Nicole Hernandez, USA Today, 25 Mar. 2026

This is in contrast to its rival diabetes injectable drug semaglutide (Ozempic), a GLP-1 receptor agonist that targets one hormone. —Emily Kay Votruba, EverydayHealth.com, 20 Mar. 2026

Retatrutide is among an emerging generation of weight loss drugs called GLP-3 agonists. —Jackie Flynn Mogensen, Scientific American, 19 Mar. 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