​BOATSWAIN (pronounced “bo’sun”; derived from “boat” and “swain,” a servant), the warrant officer of the navy who in sailing-ships had particular charge of the boats, sails, rigging, colours, anchors and cordage. He superintended the rigging of the ship in dock, and it was his duty to summon the crew to work by a whistle. The office still remains, though with functions modified by the introduction of steam. In a merchant ship the boatswain is the foreman of the crew and is sometimes also third or fourth mate.