Pharos (n.)

as a word or name for a lighthouse, literal or figurative, 1550s, extended from the name of mighty lighthouse which Ptolemy Philadelphius had built on an island off the coast of Alexandria, from Greek pharos "lighthouse," a word of unknown origin. Hence also pharology (1847) "the art or science of directing ships by means of light signals from the shore."

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Definitions of Pharos from WordNet

pharos (n.)
a tower with a light that gives warning of shoals to passing ships;
Synonyms: beacon / lighthouse / beacon light