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.-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.