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

He isn’t the only one raising the specter of a foreign adversary opposing data-center construction and slowing America’s pursuit of artificial intelligence.

From The Wall Street Journal • Jun. 14, 2026

“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

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

Despite peace overtures from the South Korean government, the North has repeatedly cast Seoul as its main adversary, and recently removed longstanding references to Korean unification from its constitution.

From Barron's • May 8, 2026

For the first time in the Cold War, American military leaders felt that they had a clear image of Russia's military capabilities—knowledge that would help the United States stay one step ahead of its adversary.

From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau

Related Words

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