Forecastle.

Ancient ships had a castle, as may be seen in the tapestry of the House of Lords, representing the Spanish Armaʹda. The term forecastle means before the castle. The Romans called the castled ships navēs turriʹtæ.

“That part of the upper deck forward of the foremast … In merchant ships, the forward part of the vessel, under the deck, where the sailors live.”—Dana: Seaman’s; Manual, p. 96.