adversarial

adversarial (comparative more adversarial, superlative most adversarial)

1. Characteristic of, or in the manner of, an adversary; combative, hostile, opposed
   • 2012 November 7, Matt Bai, “Winning a Second Term, Obama Will Confront Familiar Headwinds”, in New York Times‎:

     In polling by the Pew Research Center in November 2008, fully half the respondents thought the two parties would cooperate more in the coming year, versus only 36 percent who thought the climate would grow more adversarial.

• cooperative

• adversarial system
• adversarially