What flying-machine design did Leonardo da Vinci call an ornithopter?

Leonardo da Vinci’s ornithopter was a flapping-wing aircraft design inspired by bird flight.

Leonardo studied birds extensively and believed that understanding their wing movements could help humans fly. His notebooks contain several proposals in which a pilot would operate large wings through levers, pedals, or other mechanical linkages. The designs were not powered by an engine and were never built into a successful aircraft.

An ornithopter is defined by its flapping wings, not simply by its resemblance to a bird. Leonardo’s ideas therefore belong to the history of ornithopters, even though modern aircraft generally use fixed wings or rotating blades. A common mix-up is calling every Leonardo flying machine a helicopter; his separate aerial-screw concept used rotary motion rather than flapping wings.

Leonardo’s drawings were important as investigations of aerodynamics, anatomy, balance, and mechanical transmission, but they did not demonstrate that human-powered flight was practical.