adversarial

adjective

ad·​ver·​sar·​i·​al ˌad-vər-ˈser-ē-əl 

ˌad-və-, 

-ˈse-rē-

: involving two people or two sides who oppose each other : of, relating to, or characteristic of an adversary or adversary procedures (see adversary entry 2 sense 2)

an adversarial relationship

an adversarial system of justice with prosecution and defense opposing each other

Synonyms of adversarial

• hostile
• negative

Examples of adversarial in a Sentence

an adversarial system of justice with prosecution and defense opposing each other

the relationship between the president and the congress should not be adversarial if anything is to get done

Recent Examples on the Web

For decades, Washington relied on deterrence to counter the possibility of adversarial biological attacks—but, notably, not by threatening biological attacks of its own. — Elizabeth Sherwood-Randall, Foreign Affairs, 18 Aug. 2026

Previous Tyson Group polling cited in the memo found 72% of Americans supported government guardrails on AI, while 63% were concerned that adversarial countries such as China were developing the technology faster than the United States. — Samantha-Jo Roth, The Washington Examiner, 13 Aug. 2026

In 2010, privacy artist and researcher Adam Harvey developed a system to counter burgeoning facial recognition technology, using adversarial makeup and hair-styling techniques. — Kim Key, PC Magazine, 7 Aug. 2026

If the same adversarial inputs defeat multiple layers, those layers are redundant. — Claude Mandy, Forbes.com, 6 Aug. 2026

Word History

Etymology

adversary entry 1 + -al entry 1

First Known Use

1839, in the meaning defined above

Rhymes for adversarial

• biserial
• filarial
• malarial
• subaerial
• actuarial
• secretarial
• urticarial
• aerial
• areal
• ariel
• burial
• antimalarial

Kids Definition

adversarial

adjective

ad·​ver·​sar·​i·​al ˌad-vər-ˈser-ē-əl 

: involving two people or two sides who oppose each other

Legal Definition

adversarial

adjective

ad·​ver·​sar·​i·​al ˌad-vər-ˈser-ē-əl 

: of, relating to, or characteristic of an adversary or adversary procedures : adversary