A helicopter is a flying vehicle with a system of rotors that lift and propel it. In some cities, police officers patrol in helicopters. In some suburbs, wealthy people even commute by helicopter.
Like airplanes, helicopters travel through the air — but unlike airplanes, they don't have wings. Most helicopters have a large rotor blade on top that creates lift by spinning rapidly. Smaller rotors help the helicopter move and steer. Hospitals use helicopters for transporting patients in crisis, for whom an ambulance might not move fast enough. The word comes from Greek roots, helix, "spiral," and pteron, "wing."