agonist meaning and definition

AGONIST noun

Definition of agonist (noun)

1. the principal character in a work of fiction
   • synonyms: protagonist
2. someone involved in a contest or battle (as in an agon)
   • antonym: adversary
3. a muscle that contracts while another relaxes
   • "when bending the elbow the biceps are the agonist"
4. (biochemistry) a drug that can combine with a receptor on a cell to produce a physiological reaction