boatswain, the officer in charge of maintaining all the ship's rigging, sails, cables, anchors etc. in good repair, and in charge of all work on deck. Assisted by bosun's mates. The shrill bosun's whistle piped commands on a busy naval deck.

Typically the Senior Crewman. The man on board a ship held responsible for keeping the shrouds, sails, and masts in good repair.

foreman of the sailors aboard a merchant ship, generally responsible for their work and discipline.

Also boatswain, bos'n, bo's'n, and bo'sun, all of which are pronounced "bow-sun." A crew member responsible for keeping the hull, rigging and sails in repair.

Also boatswain. Originally head of the gang that moved the lifeboats and whaleboats on and off the ship. Essentially an NCO.