deadlight

American  

[ded-lahyt] / ˈdɛdˌlaɪt /

noun

Nautical.

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

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

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deadlight British  

/ ˈdɛdˌlaɪt /

noun

1. nautical

   1. a bull's-eye let into the deck or hull of a vessel to admit light to a cabin

   2. a shutter of wood or metal for sealing off a porthole or cabin window

2. a skylight designed not to be opened

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Etymology

Origin of deadlight

First recorded in 1720–30; dead + light ¹