(chiefly meteorology) A radar system using the Doppler effect to measure the radial velocity of detected objects, allowing moving objects (such as airplanes, precipitation, missiles, etc.) to be distinguished from stationary ones and classified by magnitude and direction of their velocity towards or away from the radar site.

(physics) The broadening of the spectral lines of a high-temperature or rapidly-rotating object due to redshifting of spectral lines from atoms and molecules moving away from the observer and blueshifting of spectral lines from atoms and molecules moving toward the observer.

Medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), and their relative velocity to the probe.