a person, group, or force that opposes or attacks; opponent; enemy; foe.

a person, group, etc., that is an opponent in a contest; contestant.

the Adversary, the devil; Satan.

of or pertaining to an adversary.

involving adversaries, as plaintiff and defendant in a legal proceeding

an adversary trial.

noun

ally , assistant , backer , friend , helper , helpmate , supporter

noun

antagonist , attacker , bad person , bandit , competitor , contestant , enemy , foe , match , opposer , opposite number , oppugner , rival , opposition , oppositionist , resister , anti , assailant , disputant , doe , foil , opponent , satan