'Deadlight' definitions:

Definition of 'deadlight'

(from WordNet)
noun
A strong shutter over a ship's porthole that is closed in stormy weather

Definition of 'Deadlight'

From: GCIDE
  • Deadlight \Dead"light`\, n. (Naut.) A strong shutter, made to fit open ports and keep out water in a storm. [1913 Webster]