Radar

n. system for locating objects by sending radio waves and recording their echoes

Radar is a system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. A transmitter emits radio waves, which are reflected by the target and detected by a receiver, typically in the same location as the transmitter. Although the radio signal returned is usually very weak, radio signals can easily be amplified. This enables a radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in many contexts, including meteorological detection of precipitation, air traffic control, police detection of speeding traffic, and by the military. It was originally called RDF (Radio Direction Finder) in Britain. The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. The term has since entered the English language as a standard word, radar, losing the capitalization in the process.
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Noun
1. measuring instrument in which the echo of a pulse of microwave radiation is used to detect and locate distant objects
(synonym) microwave radar, radio detection and ranging, radiolocation
(hypernym) measuring instrument, measuring system, measuring device
(hyponym) early warning radar
(part-meronym) dish, dish aerial, dish antenna, saucer

n. radar, system for locating objects by sending radio waves and recording their echoes

n. radar, system for locating objects by sending radio waves and recording their echoes