agonist

noun

1. a person engaged in a contest, conflict, struggle, etc., especially the protagonist in a literary work.
2. a person who is torn by inner conflict.
3. Physiology. a contracting muscle whose action is opposed by another muscle.Compare antagonist(def 3).
4. Pharmacology. a chemical substance capable of activating a receptor to induce a full or partial pharmacological response.Compare antagonist(def 5).

noun

1. any muscle that is opposed in action by another muscleCompare antagonist (def. 2)
2. a competitor, as in an agon

n.

1876, in writings on Greek drama, from Greek agonistes, literally “combatant in the games” (see agony).

n.

1. A contracting muscle that is resisted or counteracted by an antagonistic muscle.
2. A substance that can combine with a cell receptor to produce a reaction typical for that substance.

1. A muscle that actively contracts to produce a desired movement.
2. A chemical substance, especially a drug, that can combine with a receptor on a cell to produce a physiologic response. Compare antagonist.