Bulkhead

A bulkhead is a wall-like partition in a starship used to aid structural integrity.

Bulkheads are numbered and divide a ship into separate parts to help keeping its rigidity. Bulkheads in Starfleet vessels built in the 24th century, specifically of the and, were composed of  tritanium alloy and could be reinforced with shields to enhance the ship's overall structural integrity. 

In case of structural failure, a bulkhead can be beamed away and temporarily replaced by a force field. 

In 2369 the bulkheads aboard Deep Space 9 were broken by several hull breaches caused by graviton pulses of the embryonic lifeform. 

While searching the debris of the destroyed attack cruiser, Dax and O'Brien found pieces of the secondary hull and the bulkheads in the debris. 

Jadzia Dax claimed she could hear Kor snoring through the bulkheads of the USS Rio Grande in 2372. 

Elim Garak had "a sudden and somewhat violent encounter with a bulkhead" when the USS Defiant (2370) was attacked by the Dominion early in the war.