- 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
WordReference Random House Learner's Dictionary of American English © 2026
per•i•scope /ˈpɛrəˌskoʊp/USA pronunciation
n. [countable]
WordReference Random House Unabridged Dictionary of American English © 2026- Opticsan instrument for viewing objects, usually made of a tube with an arrangement of prisms or mirrors, used esp. in submarines.
per•i•scope
(per′ə skōp′),USA pronunciation n.
- Opticsan 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 esp. in submarines.
- Opticsa periscopic lens.
- back formation from periscopic 1815–25
Collins Concise English Dictionary © HarperCollins Publishers::
periscope /ˈpɛrɪˌskəʊp/ n
'periscope' also found in these entries (note: many are not synonyms or translations):