1. a person who actively opposes or is hostile to someone or something; an adversary
2. the principal character in opposition to the protagonist or hero in a drama or narrative
Usage: literary
3. a substance that interferes with or inhibits the physiological action of another
Usage: medical; biochemistry

Examples

• The union leader became the company’s main antagonist during the strike.
• In the novel, the antagonist plots to destroy the hero’s reputation.
• The two politicians were longtime antagonists in the debate over healthcare reform.
• Darth Vader serves as the primary antagonist in the original Star Wars trilogy.
• The drug acts as an antagonist to certain brain receptors.
• She found herself cast as the antagonist in their family dispute.
• The detective finally confronted his antagonist in the story’s climax.