What flying-machine concept did Leonardo da Vinci design with large flapping wings?

Leonardo da Vinci designed an ornithopter, a flying-machine concept with large flapping wings.

The word ornithopter means a machine that flies by flapping wings, echoing the motion of birds or insects. Leonardo studied bird flight, wing structure, balance, and the movement of air while developing several related sketches.

His proposed human-powered machines used wings that a pilot might operate through pedals, levers, or other mechanical linkages. They were ingenious attempts to imitate biological flight, but a person could not generate enough power with contemporary materials and mechanisms to make such a craft practical.

An ornithopter is not the same as the rotating-wing aircraft concept also associated with Leonardo. Rotors produce lift by spinning, whereas an ornithopter seeks lift and thrust through repeated wingbeats.