1. a superstructure at or immediately aft of the bow of a vessel, used as a shelter for stores, machinery, etc., or as quarters for sailors.
2. any sailors’ quarters located in the forward part of a vessel, as a deckhouse.
3. the forward part of the weather deck of a vessel, especially that part forward of the foremast.
Wordsmith Wednesdays made-up example sentences:
The common sailors all slept in the forecastle.
Rouse those dogs from the fo'c'sle!