[{"Bold_text": "noun", "List Items": ["a person who is opposed to, struggles against, or competes with another; opponent; adversary.Synonyms: foe , enemy , contestant Antonyms: friend , ally", "the adversary of the hero or protagonist of a drama or other literary work:Iago is the antagonist of Othello.", "Physiology.a muscle that acts in opposition to another.Compare agonist(def3) agonist(def3).", "Dentistry.a tooth in one jaw that articulates during mastication or occlusion with a tooth in the opposing jaw.", "Pharmacology.a drug that counteracts the effects of another drug.Compare agonist(def4) agonist(def4)."]}]