Opponent : someone who competes with or opposes another in a contest, game, or argument. Friend : a person with whom one has a bond of mutual affection, typically one exclusive of sexual or family relations. Rival : a person or thing competing with another for the same objective or for superiority in the same field of activity. Antagonist : a person who actively opposes or is hostile to someone or something; an adversary. Ally : side with or support.