Remittitur is a term with different meanings. In the context of a jury verdict, it refers to a judge's order reducing a judgment awarded by a jury when it exceeds the amount asked for by the plaintiff.
In the context of appellate procedure, it refers to an appellate court sending a case back to the trial court so that the case can be retried, or so that trial court can enter an order that conforms to the findings of the appellate court. Remittitur is a process by which jurisdiction is transferred back from the appellate court to the trial court. Remittitur divests the appellate court of the jurisdiction after it has resolved the appeal, and permits full jurisdiction over the judgment to be returned to the trial court.