cap·tain / ˈkaptən/ • n. the person in command of a ship. ∎  the pilot in command of a civil aircraft. ∎  a naval officer of high rank, in particular (in the U.S. Navy or Coast Guard) an officer ranking above commander and below commodore. ∎  an army officer of high rank, in particular (in the U.S. Army, Marine Corps, or Air Force) an officer ranking above first lieutenant and below major. ∎  a police officer in charge of a precinct, ranking below a chief. ∎  the head of a precinct's fire department. ∎  the leader of a team, esp. in sports. ∎  a powerful or influential person in a particular field: a captain of industry. ∎  a political party leader in a local district. ∎  a supervisor of waiters or bellboys.• v. [tr.] be the captain of (a ship, aircraft, or sports team).DERIVATIVES: cap·tain·cy / -tənsē/ n.

captain XIV. ME. capitain — late OF. (mod. -aine), superseding earlier chevetaigne CHIEFTAIN and chataigne, catanie — late L. capitāneus chief, f. caput, capit- HEAD.
Hence captaincy XIX.