From Longman Dictionary of Contemporary Englishperiscopeper‧i‧scope /ˈperəskəʊp $ -skoʊp/ noun [countable] TTWPMNa long tube with mirrors fitted in it, used to look over the top of something, especially to see out of a submarine
Examples from the Corpus
periscope• Rear cockpit above features a periscope that seemingly makes the front occupant's head transparent.• I've always found a periscope to be a very useful accessory in these conditions.• Their plan, which involves a periscope, works in unexpected ways.• And when they did, they moved very slowly, like a periscope.• He scorned the use of a periscope, and stood and poked his head over the parapet.• When I started circuit work that periscope, completely forgotten during the flight, made me jump just before touchdown.• We upped periscope, identified it, then downed periscope.Origin periscope (1800-1900) peri- (from Greek; PERICARDIUM) + Greek skopos “look” 