1) Beacon-bearing boat 2) Ship 1) Ls 
marine navigation and warning beacon stationed where lighthouse construction is impractical. The first lightship was the Nore (1732), stationed in ... [1 related articles]
A ship carrying a navigational warning light which is anchored in a fixed position.
[n] - a ship equipped like a lighthouse and anchored where a permanent lighthouse would be impracticable
noun a ship equipped like a lighthouse and anchored where a permanent lighthouse would be impracticable