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

The goal was to find and fix the vulnerabilities before hackers and adversarial governments like China began using similar tools to find and exploit them for espionage and sabotage. — Renee Dudley, ProPublica, 29 July 2026

Google also doesn’t claim that SynthID is invulnerable—the original paper on the technology notes that the watermark is not intended to withstand adversarial attacks. — ArsTechnica, 29 July 2026

This, the source said, should lead FIFA to engage in good faith rather than assure an adversarial posture. — Adam Crafton, New York Times, 27 July 2026

Baldur is more circumspect, irked at having temporarily lost his boat in the mishap, and unsettled by Helge’s teasing manner, which could be interpreted as either adversarial or flirtatious. — Dennis Harvey, Variety, 26 July 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