Leonardo da Vinci’s human-powered flying-machine design with flapping wings was an ornithopter.
An ornithopter is an aircraft intended to fly by flapping wings, imitating birds, bats, or insects. Leonardo studied birds in flight and produced several sketches of wing structures, harnesses, and control mechanisms during the late 15th and early 16th centuries.
Leonardo’s designs were not practical aircraft because human muscles cannot generate enough sustained power for a person-sized flapping machine. His work nevertheless helped connect artistic observation with mechanical engineering. He considered wing shape, leverage, balance, and the movement of air.
The term is broader than Leonardo’s designs: modern ornithopters can be powered by engines or motors, and some small versions use flexible wings. Leonardo’s separate “aerial screw” was a rotary lifting concept, not an ornithopter.