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

Like Field, many people who have taken these drugs, broadly known as glucagonlike peptide 1 (GLP-1) receptor agonists, have seen weight loss stagnate—and nearly a quarter haven’t seen any weight or health benefits at all. —Bethany Brookshire, Scientific American, 6 Feb. 2026

My younger brother, Jared, also developed a gambling problem after being diagnosed with RLS in 2007 and was prescribed a dopamine agonist. —J. Aaron Sanders, STAT, 4 Feb. 2026

Ozempic is a type of GLP-1 medication (glucagon-like peptide-1 receptor agonists) that regulates appetite and increases feelings of fullness. —Cara Lynn Shultz, PEOPLE, 12 Jan. 2026

The doctor confirmed that the new drug, with its third receptor agonist, will further decrease hunger while increasing the feeling of fullness. —Angelica Stabile, FOXNews.com, 12 Jan. 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