from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An arrangement of lenses and mirrors making it possible to see around obstructing objects.
from the GNU version of the Collaborative International Dictionary of English
- n. An arrangement of lenses and mirrors which enables a person to see an object in spite of intervening objects. Since the early 1900's, most commonly called periscope.
from The Century Dictionary and Cyclopedia
- n. An instrument consisting of an arrangement of lenses and mirrors in a telescopic tube, extensible vertically, by means of which it is possible to look over objects intervening between the observer and the object to be seen.
Latin altus high + Ancient Greek for "to view". (Wiktionary)