Definitions of agonist:
- noun: (biochemistry) a drug that can combine with a receptor on a cell to produce a physiological reaction
- noun: a muscle that contracts while another relaxes
Example: "When bending the elbow the biceps are the agonist"
- noun: someone involved in a contest or battle (as in an agon)
- noun: the principal character in a work of fiction
Search for agonist at other dictionaries: OneLook, Oxford, American Heritage, Merriam-Webster, Wikipedia