A plea is a foreign matter to discharge or stay the suit. A special answer showing or relying upon one or more things as a cause why the suit should be either dismissed, delayed or barred. A plea is a special answer to a bill, and differs in this from an answer in the common form, as it demands the judgment of the court in the first instance, whether the matter urged by it does not debar the plaintiff from his title to that answer which the bill requires.
Pleas are of three sorts: 1. To the jurisdiction of the court. 2. To the person of the plaintiff. 3. In bar of the plaintiff's suit.