- [U. S. Navy] An officer who ranks next above a captain; sometimes, by courtesy, the senior captain of a squadron. The rank of commodore corresponds with that of brigadier general in the army.
- [British Navy] A captain commanding a squadron, or a division of a fleet, or having the temporary rank of rear admiral.
- A title given by courtesy to the senior captain of a line of merchant vessels, and also to the chief officer of a yachting or rowing club.
- A familiar for the flagship, or for the principal vessel of a squadron or fleet.
Etymology: Prob. a corruption of commander, or Sp. comendador a knight of a military order who holds a commandery; also a superior of a monastery, fr. LL. commendare to command. Cf. Commend Command Commander