Leonardo da Vinci’s proposed flapping-wing flying machine was called an ornithopter.
The word ornithopter comes from Greek roots meaning bird and wing. Leonardo studied birds extensively, examining their wings, muscles, balance, and movement. His flying-machine sketches used those observations to imagine a craft whose wings would flap like a bird’s rather than remain fixed like those of a glider.
Leonardo produced several ornithopter concepts, including designs powered by a person’s arms or legs. The machines were generally too heavy and lacked the power needed for sustained human flight. He eventually recognized that human muscles could not provide enough energy for a large flapping aircraft.
An ornithopter is a category of aircraft, not one single Leonardo model. Modern experimental ornithopters have flown with mechanical or powered systems, but Leonardo’s Renaissance designs were never documented as successful crewed aircraft.