1876, in writings on Greek drama, from Greek agonistes, literally "combatant in the games" (see agony).
agonist ag·o·nist (āg'ə-nĭst)n.
A contracting muscle that is resisted or counteracted by an antagonistic muscle.
A substance that can combine with a cell receptor to produce a reaction typical for that substance.
A muscle that actively contracts to produce a desired movement.
A chemical substance, especially a drug, that can combine with a receptor on a cell to produce a physiologic response. Compare antagonist.