Bulkhead \Bulk"head`\, n. [See {Bulk} part of a building.] 1. (Naut.) A partition in a vessel, to separate apartments on the same deck. 2. A structure of wood or stone, to resist the pressure of earth or water; a partition wall or structure, as in a mine; the limiting wall along a water front. {Bulked line}, a line beyond which a wharf must not project; -- usually, the harbor line.