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

Hundreds of consumers are suing the manufacturers of GLP-1 receptor agonists, alleging the medications may increase the risk of a rare form of vision loss. — Melissa Rudy , Angelica Stabile, FOXNews.com, 22 Sep. 2026

This month, the US Food and Drug Administration approved the first orexin agonist treatment for narcolepsy. — Harriet Marsden, TheWeek, 20 Aug. 2026

Over the past two years, GLP-1 receptor agonists have piled up randomized trial wins in organs most had never considered when these drugs were initially approved. — Jesse M. Pines, Forbes.com, 10 Aug. 2026

The twice-a-day pill, an orexin receptor agonist that will be marketed as Orzeyful, is likely to be very appealing to patients. — Ed Silverman, STAT, 6 Aug. 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