radar
radar (rā"dar) , noun
[acronym from RAdio Detection And Ranging.]
1.
An electronic device designed to detect objects at a distance, and determine their distance from the device, by transmitting a pulse of radio waves and measuring the time required for the echo of the pulse to return to the emitting device; as, the radar showed a plane approaching rapidly. [acronym]
2.
The method of detecting objects, finding their distance, or determining their speed, by use of a radar{1} device; as, modern radar can detect objects as small as raindrops.