lighthouse

noun, plural light·hous·es [lahyt-hou-ziz] /ˈlaɪtˌhaʊ zɪz/.

1. 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.
2. 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.

noun

1. 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

n.1620s, from light (n.) + house (n.).