1. a rotating part of a machine, especially the blades of a helicopter or the spinning part of an electric motor

Examples

• The helicopter’s main rotor spun rapidly as it prepared for takeoff.
• The mechanic replaced the damaged rotor in the electric motor.
• Ice formed on the rotor blades during the winter flight.
• The tail rotor helps control the helicopter’s direction.
• A faulty rotor caused the machine to vibrate excessively.
• The wind turbine’s rotor turned slowly in the gentle breeze.