Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Sea captain \Sea" cap"tain\ The captain of a vessel that sails upon the sea.
WordNet
Wikipedia
A sea captain (also called a captain or a ship's captain or a master or a shipmaster) is a high-grade licensed mariner in ultimate command of the merchant vessel. The captain is responsible for its safe and efficient operation, including: ship's seaworthiness, ship's safety and security conditions, cargo operations, navigation, crew management and ensuring that the vessel complies with local and international laws, as well as company and flag state policies. All persons on board, particularly during navigation, including, public authorities, state authorities, officers and crew, other shipboard staff members, passengers, guests and pilots, are under the captain's authority and are his or her ultimate responsibility.
Usage examples of "sea captain".
Jane Pauley once asked me on the Today Show if I might have been a sea captain in a prior life.
He knew that because he loved the old sea captain for the way he accepted him in spite of the birthright that marked him.
The English sea captain was draining his own mug, and the old man with the meerschaum pipe was busy trying to get it to light for about the fiftieth time that night.
The fisherman, or escaped prisoner or sea captain or whoever he was, had a puzzled expression on his face.