A more thorough explanation:

Definition: Adversarius (ad-vər-sair-ee-əs) is a Latin term used in Roman law to refer to an adversary in a lawsuit.

Example: In a court case, the plaintiff and defendant are considered adversarii, as they are opposing parties with conflicting interests.

Explanation: The term adversarius is used to describe someone who is on the opposite side of a legal dispute. In a lawsuit, the adversarius is the person or party that the plaintiff is suing or that the defendant is defending against. The adversarius is essentially the opponent in the case, and their interests are in direct conflict with the other party.