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.
a periscopic lens.

Origin of periscope

First recorded in 1815–25; back formation from periscopic Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for periscope

sight, radar, sonar, viewfinder, bombsight

Examples from the Web for periscope

Historical Examples of periscope

  • The conning-tower and periscope are placed on the upper deck, as shown.

    Boys' Book of Model Boats

    Raymond Francis Yates

  • I was glad when I picked up its homely white front in my periscope.

    Danger! and Other Stories

    Arthur Conan Doyle

  • The captain turns the periscope around, scanning the waters.

    Some Naval Yarns

    Mordaunt Hall

  • He looked neither to right nor left but was still at the periscope.

    Some Naval Yarns

    Mordaunt Hall

  • This periscope was not in use and had not been above the surface.

    Some Naval Yarns

    Mordaunt Hall

British Dictionary definitions for periscope



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

Word Origin for periscope

C19: from Greek periskopein to look around; see peri-, -scope
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for periscope

viewing apparatus on a submarine, 1899, formed in English from peri- "around" + -scope "instrument for viewing." Earlier (1865) a technical term in photography. Related: Periscopic.

Online Etymology Dictionary, © 2010 Douglas Harper

periscope in Science



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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.