opponent

/əˈpoʊnənt/
noun
  1. A person who competes against or fights another in a contest, game, or argument.
    • The boxer shook hands with his opponent before the match began.
    • In the debate, each opponent presented strong arguments for their side.
    • She defeated her opponent in the final round of the chess tournament.
  2. A person who disagrees with or resists a proposal, idea, or policy.
    • He was a vocal opponent of the plan to build a highway through the forest.
    • Opponents of the new law gathered outside the capitol building to protest.
    • The senator faced fierce criticism from opponents of the healthcare bill.
adjective
  1. Acting against or in opposition; opposing.
    • She took an opponent stance on the issue, arguing against the majority.
    • The opponent forces were well prepared for the battle.
    • The opponent team played aggressively from the start.