- a tower or other structure displaying or flashing a very bright light for the guidance of ships in avoiding dangerous areas, in following certain routes, etc.
- either of two cylindrical metal towers placed forward on the forecastle of the main deck of a sailing ship, to house the port and starboard running lights.
- a fixed structure in the form of a tower equipped with a light visible to mariners for warning them of obstructions, for marking harbour entrances, etc