Source : Webster's Revised Unabridged Dictionary (1913)

Anchor light \Anchor light\ (Naut.)
   The lantern shown at night by a vessel at anchor.
   International rules of the road require vessels at anchor to
   carry from sunset to sunrise a single white light forward if
   under 150 feet in length, and if longer, two such lights, one
   near the stern and one forward.

Source : WordNet®

anchor light
     n : a light in the rigging of a ship that is riding at anchor
         [syn: {riding light}, {riding lamp}]