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

California recently passed a budget for 2025-2026 that eliminates Medicaid coverage for GLP-1 agonists for weight loss. —Joshua P. Cohen, Forbes.com, 7 Aug. 2025

According to a May 2024 KFF Health Tracking Poll, approximately one in eight U.S. adults (12 percent) report having used a GLP-1 agonist. —Lucy Notarantonio, MSNBC Newsweek, 4 Aug. 2025

O'Neil said 7-hydroxymitragynine, 7-OH, is deliberately addictive and a powerful opioid agonist many times more potent than morphine. —Natalie Neysa Alund, USA Today, 31 July 2025

Herbal and integrative support Clinical studies show that combining Chinese herbal medicine (CHM) with Western medications like GnRH agonists can improve outcomes while reducing side effects. —Dominique Fluker, Essence, 30 July 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