# agonist

/ˈæɡənɪst/ (US) · CEFR C1 · Noun

Source: https://englishreference.com/word/agonist
Updated: 2026-05-20

## Definition

a substance that causes a specific reaction in the body, like a drug that makes a muscle move or a heart beat faster.

For teachers: a substance that binds to a receptor and triggers a biological response, typically mimicking the action of a naturally occurring neurotransmitter or hormone.

## Examples

- The drug acts as an agonist for the brain's pain receptors.
- Researchers are developing a selective agonist that targets only the receptors responsible for reducing inflammation without affecting other parts of the nervous system.
- In pharmacology, an agonist differs from an antagonist by its ability to activate a receptor, whereas an antagonist merely blocks the receptor from being activated by other substances.

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