Ex parte is a legal term used to describe a type of legal proceeding where only one party is present. It literally means "on behalf of one party." Antonyms for this term would be "adversary" or "opposite party," implying that there are two parties present in a legal proceeding. This is important because in ex parte proceedings, only one party presents evidence, which can often result in an unfair outcome. By having two parties present, there is a more balanced and fair exchange of information, which can lead to better decisions. In summary, the antonyms for ex parte are adversary and opposite party.