“对手”的英文翻译主要有以下两种常见表达：
opponent
这是最常用的翻译，适用于描述竞赛、比赛中的竞争者，例如：
- The two teams are fierce opponents in the championship.
- His opponent in the debate was very persuasive.
adversary
该词多用于描述在斗争、冲突中的敌对者，带有更强烈的对抗性，例如：
- The company faced a formidable adversary in the market.
- The political rivals engaged in a bitter adversaryship.
补充说明
在网球等体育项目中，也常用 rival表示对手，如：
She has a long-standing rival in the tennis court.
若需强调“旗鼓相当”的对手，可用 equal表示，例如：
The two players are true equals on the court.
建议根据具体语境选择最贴切的词汇。