'lightship' definitions:
Definition of 'lightship'
(from WordNet)
noun
A ship equipped like a lighthouse and anchored where a permanent lighthouse would be impracticable
Definition of 'lightship'
From: GCIDE
- lightship \light"ship`\, Light-ship \Light"-ship`\(l[imac]t"sh[i^]p`), n. (Naut.) A vessel equipped like a lighthouse, carrying at the masthead a brilliant light, and moored off a shoal or place of dangerous navigation where a permanent lighthouse would be impracticable, to serve as a guide for mariners; as, the Ambrose lightship off New York was rammed and damaged in 1950 by the Santa Monica. [1913 Webster + WordNet 1.5]