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.

---

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

---

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

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

Officials hope the progress made won’t only help now, but in the future should the U.S. end up in a conflict against an adversary with more sophisticated weapons deployed in greater volumes.

From The Wall Street Journal • Jun. 2, 2026

The main rule of presidential summitry with an adversary is first do no harm.

From The Wall Street Journal • May 15, 2026

There is nothing resembling predation, and no pretense of an adversary stance on either side.

From "The Lives of a Cell" by Lewis Thomas

Related Words

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