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

Related Words

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

• adversariness
  noun
• nonadversarial
  adjective

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

But the conflict has also seen the re-emergence as a key US partner of India's traditional adversary Pakistan, which has positioned itself as a mediator, with its powerful army chief flying Friday to Tehran.

From Barron's • May 23, 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

"No adversary should mistake our current restraint with a lack of resolve."

From Barron's • May 5, 2026

"No adversary should mistake our current restraint with a lack of resolve," said Caine, who spoke alongside Hegseth.

From Barron's • May 5, 2026

First, he thanked his recent adversary Howard Fuller for preventing violence on the previous night.

From "The Best of Enemies" by Osha Gray Davidson

Related Words

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