boatswain Syllabification: (boat·swain)Pronunciation: /ˈbōsən/ (also bo'sun or bosun)Translate boatswain | into Italian | into Spanish Definition of boatswain noun a ship’s officer in charge of equipment and the crew. Origin: late Old English bātswegen (see boat, swain)boatswain in other Oxford dictionaries Definition of boatswain in the British & World English dictionary