Merriam-Webster Collegiate Dictionary - captain

 I. noun  Etymology: Middle English capitane, from Anglo-French capitain, from Late Latin capitaneus, adjective & noun, chief, from Latin capit-, caput head — more at head  Date: 14th century  1.  a.  (1) a military leader ; the commander of a unit or a body of troops  (2) a subordinate officer commanding under a sovereign or general  (3) a commissioned officer in the army, air force, or marine corps ranking above a first lieutenant and below a major  b.  (1) a naval officer who is master or commander of a ship  (2) a commissioned officer in the navy ranking above a commander and below a commodore and in the coast guard ranking above a commander and below a rear admiral  c. a senior pilot who commands the crew of an airplane  d. an officer in a police department or fire department in charge of a unit (as a precinct or company) and usually ranking above a lieutenant and below a chief  2. one who leads or supervises: as  a. a leader of a sports team or side  b. headwaiter  c. a person in charge of hotel bellhops — called also bell ~  3. a person of importance or influence in a field ~s of industry  • ~cy noun  • ~ship noun  II. transitive verb  Date: 1598 to be ~ of ; lead ~ed the football team