COMMANDER, noun

1. A chief; one who has supreme authority; a leader; the chief officer of an army, or of any division of it. The term may also be applied to the admiral of a fleet, or of a squadron, or to any supreme officer; as the commander of the land or of the naval force; the commander of a ship.

2. One on whom is bestowed a benefice or commandry.

3. A heavy beetle or wooden mallet, used in paving, etc.

4. An instrument of surgery.