查壹下柯林斯詞典：
opponent：a person who opposes another in a contest, battle, etc
enemy:a person hostile or opposed to a policy, cause, person, or group, esp one who actively tries to do damage
adversary:a person or group that is hostile to someone
可見，adversary=enemy是懷有仇恨的對手，既敵人。而opponent僅僅指代競爭或比賽中的對手而已。