What is the name of the instrument used to measure wind speed?

An anemometer is the instrument used to measure wind speed.

The most familiar design is the cup anemometer, which has three or four cups mounted on horizontal arms. Wind pushes the cups around a central spindle, and the rotation rate is converted into a wind-speed reading. Propeller anemometers use a small fan-like rotor instead and usually point into the wind.

The word comes from the Greek word anemos, meaning wind. Early mechanical anemometers appeared in Europe centuries ago, while modern versions may use ultrasonic pulses, laser measurements, or heated wires with no moving parts. A common mix-up is confusing anemometers with wind vanes: an anemometer measures speed, while a wind vane shows direction. Weather stations often use both instruments together, and aviation, marine forecasting, engineering, and wind-energy projects all depend on their readings.