Commander

Commander is a military rank which is also sometimes used as a military title depending on the individual customs of a given military service. Commander is also used as a rank or title in some organizations outside of the military, particularly in police and law enforcement. Commander is a military rank used in many navies and some air force but is very rarely used as a rank in armies. The rank (originally "Master and Commander") originated in the 18th and early 19th centuries to describe lieutenants that were "captains" of smaller ships such as sloops or brigs. The Royal Navy shortened "Master and Commander" to just "Commander" in 1794. A commander in the British Royal Navy is above the rank of lieutenant-commander, below the rank of captain, and is equivalent in rank to a lieutenant colonel in the army. A commander may command a frigate, destroyer, submarine, aviation squadron or shore installation, or may serve on a staff. A Commander in the Royal Australian Navy (RAN) is... full article at wikipedia