To make a decision (in a legal case or proceeding), as where a judge or arbitrator rules on some disputed issue or claim between the parties. To study and settle (a dispute or conflict): The principal adjudicated the students' quarrel. To act as a judge of (a contest or an aspect of a contest). To make a decision in a legal case or proceeding: a judge adjudicating on land claims. To study and settle a dispute or conflict. To act as a judge of a contest.