What is the definition of a "Bulkhead" in an aircraft?

The definition of a "Bulkhead" in an aircraft refers to any dividing wall within the plane. Bulkheads serve multiple important functions, such as providing structural support and separating different sections of the cabin, which can enhance passenger safety and comfort. They may also house essential components like emergency exits or storage compartments. The distinction of bulkheads lies in their role as physical barriers that define areas within the aircraft, rather than being furniture or part of the aircraft's exterior structure.

The other choices pertain to different aspects of the aircraft. First-class seats are specifically designed for comfort and luxury but are not what a bulkhead represents. The wooden floor mentioned does not accurately describe common airplane flooring, which is typically made of lightweight materials, and is not associated with a bulkhead. Lastly, the outer shell of the plane refers to the fuselage, which is the primary structure holding the aircraft together but distinct from the internal dividing walls called bulkheads.