Captain is both a nautical term and a military rank. The word came to English via French from the Latin capitaneus ("chief") which is itself derived from the Latin word for "head" (caput).
The term has different meanings both at sea and in the military. Confusion between the three types of captain (nautical, naval and army) often exists in literature, drama and real life. The customs indicated are necessary to avoid confusion at sea when the question of "Who is in charge of the ship?" may be a matter of life and death.
Captain is the legal status of the master of a ship at sea and, on most legal documents in the merchant shipping industry, he / she is referred to as the Master. A nautical captain may be a civilian or a naval commissioned officer of any rank. As the commander of a vessel under way, a nautical captain has enormous legal powers, including the right to use deadly force to suppress piracy and mutiny. Mutiny is not simply the crime of disobeying the lawful orders of a nautical captain at sea, but rather doing so with the intent of taking over the ship. The captain of a ship at sea is in absolute command of that vessel even if higher-ranking persons are aboard. If higher-ranking persons give orders to the nautical captain, such persons are very careful to say what they want done rather than specifying how the orders are to be carried out, because even higher rank does not give them the right to interfere in how a captain runs the ship.
The officer who is ranked immediately below the Captain is designated the First Officer, or "Chief Mate" (also Executive Officer or First Lieutenant), and is responsible for implementing the orders of the Captain as well as conferring with the Captain on matters concerning the ship. This "second in command" is typically responsible (along with the senior enlisted petty officer) for maintaining minor discipline on the ship.
In older times, a Captain was a nobleman given responsibility over a ship, but was not likely to have any nautical experience. The next officer of the ship would be the Ship's Master, who would carry out the executive functions of a Captain, while the Captain filled a ceremonial and legal role.
is the rank of a commissioned officer
or Rear Admiral
(1 star). Naval officers below the rank of Captain who are assigned to command a ship are addressed as captain while aboard that ship, by nautical custom. A naval captain traveling aboard a vessel s/he does not command is never referred to by rank to avoid confusion with the nautical captain, who remains in charge of the entire ship (including the passengers who outrank the nautical captain).
Captains with field naval commands generally command ships of cruiser size or larger. The more senior the officer, the larger the ship. Commanders of aircraft carriers can be Rear Admiral, but generally, ship commanders are of Captain rank or lower. Also, many Captains are either retired or have desk jobs.
United States usage
In the US military, colonel is the equivalent rank of captain in the Army, Marine Corps, and Air Force.
Within a United States nuclear aircraft carrier, it is not unusual for both the commanding officer and the excutive officer to be ranked captain.
The captain in the naval sense represents the sixth step in the progression: Ensign, Lieutenant Junior Grade, Lieutenant, Lieutenant Commander, Commander, Captain, Commodore, and various ranks of Admiral.
Military and Air Force
Captain insignia of US Army and Air Force
In armies, marines and some air forces, Captain is the rank of a commissioned officer that is a rank below a Major. The military rank of Captain is ranked three steps lower than a naval Captain, and has no special authority with respect to a ship and is just another passenger or crew member whilst on board.
In the United States Army, United States Marine Corps, and United States Air Force, a captain's insignia consists of two silver bars. In the British Army and Royal Marines the insignia is a vertical row of three pips (sometimes called "stars").
Captains in the army generally command companies, which are one step below battalions.
Note that Marine units ("ship's soldiers", often responsible for security on modern warships and at embassies, as well as their amphibious assault and expeditionary duties) use rank designations similar to that of the army for both all ranks.
The United States Air Force uses a rank structure similar to the army, while the United Kingdom's Royal Air Force and the air forces of many Commonwealth countries, use a unique rank structure, in which a Group Captain is equivalent to the naval rank of captain.
See also Military unit.
In commercial aviation, a pilot in command of an aircraft is often referred to as a "captain." This practice began with the flying boats of the 1930s and quickly spread to most of the airline industry. Most airline captains wear uniforms with four bars on the sleeve and epaulet (imitating the rank basis of the rank insgnia in both the US and Royal Navies) although this varies from company to company.
See also: military rank and comparative military ranks
Most sports teams also have captains: