Captain

1. The person lawfully in command of a vessel. "Captain" is an informal title of respect given to the commander of a naval vessel regardless of his or her formal rank; aboard a merchant ship, the ship's captain is called her master.
2. A naval officer with a rank between commander and commodore.
3. In the U.S. Navy, U.S. Coast Guard, U.S. Public Health Service, and National Oceanic and Atmospheric Administration, a commissioned officer of a grade superior to a commander and junior to a rear admiral (lower half), equal in grade or rank to a U.S. Army, U.S. Marine Corps, or U.S. Air Force, or U.S. Space Force colonel.