UNDECIMVIR, a magistrate among the ancient Athenians, who had ten colleagues or associates joined with him in the same commission. The functions of the undecimviri at Athens were much the same with those of the late prévôts de maréchaussée in France. They took care of the apprehending of criminals; secured them in the hands of justice; and when they were condemned, took them again into custody, that the sentence might be executed on them. They were chosen by the tribes, each tribe naming its own; and as the number of the tribes after Callisthenes was but ten, which made ten members, a scribe or notary was added, which made the number eleven.