bulkhead

noun

1. A vertical partition dividing the hull into separate compartments; often made watertight to prevent excessive flooding if the ship's hull is breached.

   “Lastly, Lundberg went belowdecks to inspect the boat's bulkheads and hull—for what, it was not clear, since he had absolutely no knowledge of steamboat design.”

2. A similar partition in an aircraft or spacecraft, or some rail vehicles.

   “For rigidity, two bulkheads are provided which are welded to the sides and underframe and which separate the cabs from the engine room.”

   “Folding blinds are fitted to the cab bulkhead windows and sunblinds at the driving windows.”

3. A partition or panel through which connectors pass, or a connector designed to pass through a partition.
4. A pressure-resistant sealed barrier to any fluid in a large structure.
5. A retaining wall along a waterfront.
6. (Maine)A cellar hatchway.

   “She bumped her noggin on the bulkhead above the doorway, smiled in apology for her presumed clumsiness.”