1. In Literature and Drama:
* A character who opposes the protagonist: This is the most common usage. The antagonist is the primary source of conflict in a story. They often have opposing goals or values to the protagonist, creating tension and driving the plot forward.
* Examples: Darth Vader in Star Wars, Voldemort in Harry Potter, Lady Macbeth in Macbeth.
2. In Pharmacology:
* A drug or substance that blocks the action of another drug or substance: Antagonists work by binding to the same receptors as the other substance, but without triggering a biological response. This effectively prevents the other substance from working.
* Examples: Beta-blockers are antagonists that block the action of adrenaline, while antihistamines block the action of histamine.
3. In Biology:
* A muscle that opposes the action of another muscle: Muscles work in pairs, with one muscle contracting to move a joint and the other muscle relaxing. The muscle that opposes the action of the primary muscle is called the antagonist.
* Example: The biceps muscle flexes the elbow, while the triceps muscle extends the elbow. The triceps is the antagonist to the biceps.
4. In Competitive Sports:
* An opponent or competitor: This is a more general usage and is often used in the context of a competition or game.
* Examples: The antagonist in a chess match is the opponent, while in a boxing match, the antagonist is the other boxer.
To clarify the meaning of "antagonist" in any given situation, consider the context. If you're reading a novel, it likely refers to the character opposing the protagonist. If you're reading about medicine, it likely refers to a drug that blocks the action of another.