Source : Webster's Revised Unabridged Dictionary (1913)

Pharos \Pha"ros\, n. [L., fr. Gr. ?, fr. ? an island in the Bay
   of Alexandria, where king Ptolemy Philadelphus built a famous
   lighthouse.]
   A lighthouse or beacon for the guidance of seamen.

         He . . . built a pharos, or lighthouse.  --Arbuthnot.

Source : WordNet®

pharos
     n : a tower with a light that gives warning of shoals to passing
         ships [syn: {beacon}, {lighthouse}, {beacon light}]