radar gun

noun

1. a small, handheld Doppler radar device used to measure the speed of vehicles or other moving objects.

radar gun

1. A usually hand-held device that measures the velocity of a moving object by sending out a continuous radio wave and measuring the frequency of reflected waves.
2. See more at Doppler effect

Example Sentences

It’s a game you play with the California Highway Patrol, figuring out where they’re going to hide their radar guns, then getting in the slow lane like you just got back from church.

From Vox