Periscope
Part of speech: noun
Definition: A form of viewing device that allows the viewer to see things at a different height level and usually with minimal visibility. A general or comprehensive view.
Telescope
Part of speech: noun
Definition: A monocular optical instrument possessing magnification for observing distant objects, especially in astronomy.Any instrument used in astronomy for observing distant objects (such as a radio telescope).
Part of speech: verb
Definition: To extend or contract in the manner of a telescope.