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

Retatrutide is among an emerging generation of weight loss drugs called GLP-3 agonists. —Jackie Flynn Mogensen, Scientific American, 19 Mar. 2026

If any medication—or rather, movement—has defined health and wellness over the past few years, GLP-1 agonists are irrefutably it. —Julia Sullivan, Allure, 6 Mar. 2026

Natural products inspired by organisms include GLP-1 receptor agonists for weight loss, spider and snake venoms, and compounds from plants and fungi with potential uses in pain relief and cancer treatment. —Hanna Wickes, Charlotte Observer, 6 Mar. 2026

The reports also show that adult obesity rates may be slowing as a result of public health policies and the introduction of GLP-1 agonists. —Ryan Mancini, The Hill, 26 Feb. 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