An upright wall within the hull of a ship that separates different structural areas or rooms. Watertight bulkheads are heavily engineered to prevent flooding from spreading if the hull is breached. In everyday naval and marine slang, the term is used for any interior wall, regardless of its structural importance.
Heard on the job
Secure that gear against the aft bulkhead before we hit rough water.
Insider tip
Never call it a wall on a ship. Floors are decks, ceilings are overheads, and walls are bulkheads.