deadlight

[ ded-lahyt ]

/ ˈdɛdˌlaɪt /

a strong shutter able to be screwed against the interior of a porthole in heavy weather.

a thick pane of glass set in the hull or deck to admit light.

Origin of deadlight

First recorded in 1720–30; dead + light¹

As the deadlight had been closed over the port, the state-room was illumined only by a gray half-gloom from the cabin.

The Harbor Master |Theodore Goodridge Roberts
Under this head may also be mentioned the Funa'l or Deadlight, which was lighted in some churchyards at night.

Notes & Queries, No. 27. Saturday, May 4, 1850 |Various
He drew back to avoid a brick that threatened to enter the deadlight, and the conversation ended.

The Grain Ship |Morgan Robertson
Remembering his embarrassment of the morning, Denman did not seek the deck, but looked through his deadlight.

The Wreck of the Titan |Morgan Robertson

It was hot in the room, and rather dark, as the deadlight to the poop-deck was fogged by sea water.

Isle o' Dreams |Frederick F. Moore

deadlight

/ (ˈdɛdˌlaɪt) /

nautical

a skylight designed not to be opened