Definition of "agonist" in English

noun

1. Someone involved in a contest or battle (as in an agon), protagonist.

2. The muscle that contracts while the other relaxes.

   • When bending the elbow, the biceps is the agonist.

3. (biochemistry, pharmacology) A molecule that can combine with a receptor on a cell to produce a physiological reaction.

   • Acetylcholine is an agonist at the cholinergic receptor.