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

Nutter, he explains, has spent years writing sharp, absurdist songs and musicals that have remained largely under the radar.

From Los Angeles Times • Apr. 15, 2026

If the phrasing pings on your internal generative AI radar, you’re not alone.

From Barron's • Apr. 14, 2026

Detection is the foundation: radar, radio-frequency sensing, acoustic systems and electro-optical cameras that establish airspace awareness before a threat materializes.

From MarketWatch • Apr. 13, 2026

"You could say we are putting space careers on their radar," she said.

From BBC • Apr. 8, 2026

On the last night of July, South Vietnamese sailors on patrol boats fired missiles at radar stations in North Vietnam.

From "Most Dangerous: Daniel Ellsberg and the Secret History of the Vietnam War" by Steve Sheinkin

Related Words

• sonar