περισκόπιον

The Greek word periscopion (περισκόπιον) combines peri ('around') and skopein ('to look'). It literally means 'looking around.' Ancient Greeks didn't invent the optical device—they invented the concept. The word itself is Greek, but the technology waited two thousand years.

In 1854, French physicist Hippolyte Marié-Davy built the first practical submarine periscope—an arrangement of mirrors and lenses in a rotating tube that let a submerged vessel see above water. He called it a periscope, borrowing the ancient Greek term for his entirely modern invention.

But the real breakthrough came in 1902, when American engineer Simon Lake patented an improved submarine periscope design that became the naval standard. Lake's patent wasn't for the word—which was already established—but for the hardware that made submarines genuinely useful as weapons.

The periscope is now iconic in submarine warfare, cartoons, and children's games. Every submarine that sank a ship, every naval blockade, every submarine rescue operation started with what an ancient Greek word had already named: looking around from inside concealment.