There are several synonyms for the word "unmanned aerial vehicle". These include drone, UAV, quadcopter, and flying robot. Drones have become increasingly popular in recent years due to their ability to fly without a human pilot. They are commonly used in military operations and for aerial surveillance. UAV is another synonym that is often used interchangeably with drone. Quadcopters are a type of drone that uses four rotors for lift and maneuverability. Finally, "flying robot" is a more general term that can refer to any unmanned aircraft that is designed to fly autonomously or remotely controlled.