adversary

American  

[ad-ver-ser-ee] / ˈæd vərˌsɛr i /

noun

adversaries plural

1. a person, group, or force that opposes or attacks; opponent; enemy; foe.

   Antonyms:

   ally

2. a person, group, etc., that is an opponent in a contest; contestant.

3. the Adversary, the devil; Satan.

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adjective

1. of or relating to an adversary.

2. involving adversaries, as plaintiff and defendant in a legal proceeding.

   an adversary trial.

adversary British  

/ ˈædvəsərɪ /

noun

1. a person or group that is hostile to someone; enemy

2. an opposing contestant in a game or sport

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adjective

1. the US term for adversarial

Synonym Usage

Adversary, antagonist mean a person or a group contending against another. Adversary suggests an enemy who fights determinedly, continuously, and relentlessly: a formidable adversary. Antagonist suggests one who, in hostile spirit, opposes another, often in a particular contest or struggle: a duel with an antagonist.

Other Word Forms

Derived Forms

• adversariness
  noun
• nonadversarial
  adjective

Inflected Forms

Nouns

• adversaries
  plural

Etymology

Origin of adversary

First recorded in 1300–50; Middle English adversarie, from Latin adversārius; equivalent to adverse + -ary; replacing Middle English adversere, from Anglo-French

Explanation

An adversary is an enemy or someone who opposes someone else. In tennis, you stand across the net from your adversary. Adversary is related to the word adverse, meaning "against or contrary" — so think of an adversary as someone whom you are fighting against. If you're the undefeated chess champion, you have bested every single one of your adversaries. Adversary is derived from a Latin word meaning "against."

Example Sentences

“There is this augmentation of Martian energy, this feeling of needing to go up against an adversary, this feeling of needing to react quickly,” he said.

From The Wall Street Journal • Jun. 13, 2026

Pyongyang has repeatedly shunned efforts by the South Korean government to improve relations, calling Seoul its most "hostile" adversary.

From Barron's • Jun. 5, 2026

If the government wants to know whether a model can meaningfully assist cyberattacks, biological misuse or autonomous weapons development, it shouldn’t publish a checklist every lab can optimize against and every adversary can study.

From The Wall Street Journal • May 18, 2026

One of President Donald Trump's favorite metaphors is that he's got the cards -- that through the might of the United States and his own acumen he can overpower any adversary.

From Barron's • May 11, 2026

Unconsciously he tried to impress them as he walked to the ring, as if they were his adversary and not the other fighter.

From "145th Street: Short Stories" by Walter Dean Myers

Related Words

• antagonist
• attacker
• competitor
• enemy
• foe
• opponent
• rival