Bulkhead

[1] A structural partition that separates compartments. This is generally a metal wall that extends from one side of a vehicle to the other. In the engine compartment, you would find a radiator bulkhead near the front and a firewall near the back. Another bulkhead separates the passengers from the trunk. The dashpanel is also a bulkhead.
See also rear bulkhead.
[2] On a public service vehicle (i.e., taxi, limo), partition at the front between the driver and passenger accommodation.
[3] Vertical partition walls which separates the interior of a ship into compartments or rooms.
[4] In fuselages, a major structural transverse dividing wall providing access between several internal sections, or a strengthened and sealed wall at the front and rear designed to withstand the differential pressure required for pressurization.
[5] In power plant nacelles, a structure serving as a firewall.
[6] A masonry or timber partition to retain earth, as in a tunnel or along a waterfront.
See also afterpeak bulkhead, collision bulkhead, forepeak bulkhead, screen bulkhead, swash bulkhead