To whirr means to make a continuous, buzzing, vibrating sound, like the noise of something spinning or moving rapidly. When a hummingbird's wings beat so fast they become a blur, they whirr. A computer fan whirrs as it spins to keep the processor cool. An old film projector whirrs as it runs the movie reel through its gears.

The word captures both the sound and the feeling of rapid motion. You might hear the whirr of a blender mixing a smoothie, or the whirr of bicycle wheels spinning fast downhill. A toy helicopter's rotors whirr as they lift it into the air.

Writers often use whirr to bring mechanical scenes to life: “The factory floor was filled with the whirr of sewing machines.” The word itself sounds like what it describes, which makes it memorable and fun to use. When something makes that distinctive buzzing, spinning sound, whirr captures it perfectly.