opponent

opponent, competitor, enemy, foe, rival

这些名词均有“对手、敌手”之意。
opponent: 最常用词，通常指在争论、辩论、竞选或竞赛以及其它各种矛盾冲突中站在对立面的“对手”或“敌手”。
competitor: 指为同一目标或目的竞争者，一般无感情色彩。
enemy: 多指充满敌意的仇敌。
foe: 语气较强，多用于书面文字和诗歌中，指不仅敌对，而且很危险，怀有很深的敌意。
rival: 指与某人目标一致而想赶上或超过他的人，匹敌者。

名词 opponent:

1. a contestant that you are matched against
   同义词：opposition, opposite
2. someone who offers opposition
   同义词：adversary, antagonist, opposer, resister

形容词 opponent:

1. characterized by active hostility
   同义词：opposing

1. He was assailed by his political opponent.
   他遭到政敌的攻击。
2. I tried to comfort him after he was defeated by his opponent.
   他被对手击败后，我尽力安慰他。
3. He jeered at a defeated opponent.
   他嘲弄被击败的对手。
4. He is slashing wildly at his opponent with a sword.
   他正用剑疯狂地朝对手乱砍。
5. My friend, Crawley, has always been a fanatical opponent of Mr Lane's Radical Progressive Party.
   我的朋友Crawley一直是Lane先生激进党的一名狂热反对者。
6. Never underestimate your opponent.
   千万不要低估对手。
7. She is one of the strongest opponents of tax reform.
   她是税收改革最强烈的反对者之一。
8. His opponent did not stand a chance.
   他的对手毫无取胜的机会。

op.po.nent

n.（名词）
One that opposes another or others in a battle, contest, controversy, or debate.
对手：在争论、辩论、战争、对抗或其它口头论战中反对对方或其他人的人
adj.（形容词）
Acting against an antagonist or opposing force:
对立的：作为反面人物的，反对的：
例句：
opponent armies.
敌军

Located in front.
位于前方的，首要的

来源：
Latin oppônôns oppônent- [present participle of] oppônere [oppose] * see oppose
拉丁语 oppônôns oppônent- [] oppônere的现在分词 [对抗] *参见 oppose

【引伸】
oppo.nency
n.（名词）
<参考词汇><同义词>opponent,adversary,antagonistThese nouns all mean one who offers opposition.Anopponent opposes, resists, or combats:
这些名词都指持反对意见的人。一个opponent 反对、抵抗或反抗：
例句：
.two men, one . . . a zealous supporter and the other a zealous opponent of the system pursued. (Macaulay).
.两种人，一种…是对一种体系的热心支持者，另一种是激进反对者. （麦考利）。

Adversary suggests a more formidable opponent and can imply animosity:
Adversary 暗含难以对付的对手，而且可能产生敌意：
例句：
.the Adversary of God and Man,/Satan . (John Milton).
.上帝和人类的对手/，撒旦 . （约翰·弥尔敦）。

例句：
.And do as adversaries do in law,/Strive mightily, but eat and drink as friends. (Shakespeare).Anantagonist is an actively hostile opponent:
.按法律的要求做事，/勇敢地战斗，但是要友好地生活. （莎士比亚）。Antagonist 意思是敌意很强烈的反对者：

例句：
.He that wrestles with us strengthens our nerves, and sharpens our skill.Our antagonist is our helper. (Edmund Burke).See also Synonyms at enemy
.和我们搏斗的对手使我们士气大增，而且提高了技巧。我们的对手是我们的救星. （埃德蒙·伯克）参见同义词 enemy