(1):

(n.) A chief; one who has supreme authority; a leader; the chief officer of an army, or of any division of it.

(2):

(n.) An officer who ranks next below a captain, - ranking with a lieutenant colonel in the army.

(3):

(n.) The chief officer of a commandery.

(4):

(n.) A heavy beetle or wooden mallet, used in paving, in sail lofts, etc.