IPA: /ˈboʊs.wən/
KK: /ˈboʊsən/
A person on a ship who is responsible for the maintenance of the ship's hull and equipment.
The boatswain called the crew to prepare the ship for departure.
Boatswain → The word originates from Middle English *bocewain*, which is derived from the Old English *bōc* (meaning a boat) and *swain* (meaning a young man or servant). A boatswain is essentially a servant or officer in charge of the equipment and crew of a ship, particularly concerning the boats.
Think of a 'young man' ('swain') who is responsible for the 'boat' ('bōc') — that's why a boatswain is in charge of the ship's equipment.