Dictionary.net

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 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.

In the United States, a retired naval officer ranking between a captain and a rear admiral; in Great Britain, the commander of a squadron.

The commander of a squadron or detachment of ships: the leading ship of a fleet of merchantmen.

The commander of a squadron of vessels.

n. [Italian] In the Royal Navy, the commander of a squadron, having rank immediately below that of rear-admiral; —the highest rank in the navy of the United States; —the senior captain in a fleet of merchantmen.

The captain who commands a squadron of ships.