- 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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for 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.
He looked neither to right nor left but was still at the periscope.
This periscope was not in use and had not been above the surface.
- 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
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
Online Etymology Dictionary, © 2010 Douglas Harper
- 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.