military rank (OF-2)
Captains are officers in an army. In a navy, the commander of an entire ship is called "Captain" even if he is actually a lower rank. A Navy Captain rank is equal to the army rank of colonel. Another type of captain may command a merchant vessel or other ship that is not in a navy.
There are also captains in other uniformed organisations, including the police. A leader of a sports team is also called a captain, as well as the pilot of an airliner.