radar

American  

[rey-dahr] / ˈreɪ dɑr /

noun

1. Electronics. a device for determining the presence and location of an object by measuring the time for the echo of a radio wave to return from it and the direction from which it returns.

2. a means or sense of awareness or perception.

   lobbyists working under the media's radar.

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radar British  

/ ˈreɪdɑː /

noun

1. Former name: radiolocation.  a method for detecting the position and velocity of a distant object, such as an aircraft A narrow beam of extremely high-frequency radio pulses is transmitted and reflected by the object back to the transmitter, the signal being displayed on a radarscope. The direction of the reflected beam and the time between transmission and reception of a pulse determine the position of the object

2. the equipment used in such detection

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radar Scientific  

/ rā′där /

1. A method of detecting distant objects and determining their position, speed, material composition, or other characteristics by causing radio waves to be reflected from them and analyzing the reflected waves. The waves can be converted into images, as for use on weather maps.

2. The equipment used in such detecting.

3. See also Doppler effect lidar sonar

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radar Cultural  

1. A method of finding the position and velocity of an object by bouncing a radio wave off it and analyzing the reflected wave. Radar is an acronym for ra dio d etection a nd r anging.

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Discover More

Police use radar techniques to determine the speed of automobiles.

Other Word Forms

• antiradar noun

Etymology

Origin of radar

1940–45, ra(dio) d(etecting) a(nd) r(anging)

Compare meaning

How does radar compare to similar and commonly confused words? Explore the most common comparisons:

• sonar vs. radar

Explanation

Radar is a system for locating objects by bouncing radio waves off of them. Air traffic controllers use radar to keep track of exactly where airplanes are. Radar is a scientific method of figuring out where objects are — it's used today by the Coast Guard, astronomers, and the military, among others. Researchers in the late 1800's and early 1900's realized that radio waves could be reflected off solid objects, and by World War II radar was frequently used to detect ships and planes. The name radar is a shortened form of the phrase "radio detecting and ranging."

Example Sentences

Ships and coastal radar can detect rapid changes, but only over limited areas.

From Science Daily • Apr. 22, 2026

Recent transformations of the Tifani illustrate how shadow-fleet tankers try to move under the radar.

From The Wall Street Journal • Apr. 22, 2026

Gaines said his work was still under the radar during his first L.A. show at Leo Castelli Gallery, and only two pieces sold.

From Los Angeles Times • Apr. 21, 2026

This should be on investors’ radar as oil stocks fall, providing good entry points.

From MarketWatch • Apr. 18, 2026

Air Force’s early-warning radar system picked up what looked very much like a Soviet missile attack.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

Related Words

• sonar