ˈperəˌskōp noun
Etymology: International Scientific Vocabulary peri- + -scope
: an optical instrument by which an observer (as on a submerged submarine or in work with highly radioactive materials) looks through or as if through an eyepiece into a mirror or totally reflecting prism attached at an angle of 45 degrees to one end of a tube containing a system of lenses and obtains an otherwise obstructed field of view from another mirror or prism correspondingly attached to the other end of the tube
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