periscope

American  

[per-uh-skohp] / ˈpɛr əˌskoʊp /

noun

1. an optical instrument for viewing objects that are above the level of direct sight or in an otherwise obstructed field of vision, consisting essentially of a tube with an arrangement of prisms or mirrors and, usually, lenses: used especially in submarines.

2. a periscopic lens.

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periscope British  

/ ˈpɛrɪˌskəʊp /

noun

1. any of a number of optical instruments that enable the user to view objects that are not in the direct line of vision, such as one in a submarine for looking above the surface of the water. They have a system of mirrors or prisms to reflect the light and often contain focusing lenses

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periscope Scientific  

/ pĕr′ĭ-skōp′ /

1. An instrument that has angled mirrors or prisms and allows objects not in the direct line of sight to be seen, often used on submarines and in military reconnaissance.

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Etymology

Origin of periscope

First recorded in 1815–25; back formation from periscopic

Example Sentences

Horne quotes contemporaries calling the headquarters “a submarine without a periscope”: a huge blunder when facing the Wehrmacht's speedy, flexible operational plans.

From Salon

The Normandie crew spotted its periscope poking through the waves and sprang into action.

From Seattle Times

You can sit at the controls and peer through periscopes in a submarine room removed from attack submarine USS Greenling.

From Seattle Times

In the pond at Manito Park, a moose waded in small circles, standing neck-deep in the murky water, head poking out like a periscope.

From Seattle Times

The order will see Thales Glasgow continue a 100-year tradition of making periscopes for Royal Navy submarines.

From BBC