Pronunciation: (bulk'hed"),[key] —n. 1. Naut.any of various wall-like constructions inside a vessel, as for forming watertight compartments, subdividing space, or strengthening the structure.
2. Aeron.a transverse partition or reinforcing frame in the body of an airplane.
3. Civ. Engin. a. a partition built in a subterranean passage to prevent the passage of air, water, or mud.
b. a retaining structure of timber, steel, or reinforced concrete, used for shore protection and in harbor works.
4. Building Trades. a. a horizontal or inclined outside door over a stairway leading to a cellar.
b. a boxlike structure, as on a roof, covering a stairwell or other opening.