|1.||Compare antagonist any muscle that is opposed in action by another muscle|
|2.||a competitor, as in an agon|
|[C17: from Greek agōn|
agonist ag·o·nist (āg'ə-nĭst)
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.