What does "commissioner" mean?

Commissioner: An officer having charge of some department or bureau of the public service. Herbert was first commissioner of the Admiralty. Macaulay. The commissioner of patents, the commissioner of the land office, the commissioner of Indian affairs, are subotdinates of the secretary of the interior. Bartlett. Commissioner of deeds, an officer having authority to take affidavits, depositions, acknowledgment of deeds, etc., for use in the State by which he is appointed. [U. S.] -- County commissioners, certain administrative officers in some of the States, invested by local laws with various powers in reference to the roads, courthouses, financial matters, etc., of the county. [U. S.]