noun, often attributive
ra·dar | \ˈrā-ˌdär \

Definition of radar 

1 : a device or system consisting usually of a synchronized radio transmitter and receiver that emits radio waves and processes their reflections for display and is used especially for detecting and locating objects (such as aircraft) or surface features (as of a planet)

2 : range of notice fell off the radar after losing their first three games

Examples of radar in a Sentence

The approaching planes were detected by radar.

Recent Examples on the Web

At least one has been operating under the radar somewhere in the U.S. since 2014, according to a research paper . Washington Post, "‘It keeps us safe’: An NYC bathroom set up to stem overdoses," 13 July 2018 Unfortunately for the sake of flying under the radar, people are going to keep talking about Menne's golf game. Katherine Fitzgerald, azcentral, "Xavier Prep's Ashley Menne is the next big thing to hit Arizona high school athletics," 12 July 2018 Then there’s Taylor McFerrin, the elusive, elastic vocalist, beat boxer and synth player (oh, and Bobby McFerrin’s son) who has existed under the radar since his 2014 solo LP, Early Riser. Molly Eichel, Philly.com, "Album reviews: SOPHIE, Dierks Bentley, R + R = Now," 12 July 2018 But one threat has more or less flown under the radar: Some reefs lack enough bird poop. Jason Daley, Smithsonian, "Coral Reefs Need Fewer Rats and More Bird Poo," 12 July 2018 The vet-to-farmer trend is still under the radar — the USDA began recording the number of people who fit the profile just last year. Tracy Saelinger, Woman's Day, "Gardening Led This Veteran to a New Life of Hope and Healing," 11 July 2018 Some of these cases were followed by local media at the time but others, such as Grant's murder, were under the radar. Pete Corson, ajc, "How the AJC covered the events in the "ATL Homicide" pilot," 11 July 2018 Janelle Sing, still flying under the radar, was the design director for Saludos before turning to painting full-time. Katie Kiefner, Vogue, "Send All of Your Summer Thank You Notes on This Stunning Stationery," 10 July 2018 And, what trend stories may have gone under the radar? Gary Trust, Billboard, "Chart Beat Podcast: BTS, Camila Cabello, Cardi B, Drake, Ella Mai & More Highlight the Best of 2018 … So Far," 28 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'radar.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of radar

1941, in the meaning defined at sense 1

History and Etymology for radar

radio detecting and ranging

Keep scrolling for more

Learn More about radar

Statistics for radar

Last Updated

13 Oct 2018

Look-up Popularity

Time Traveler for radar

The first known use of radar was in 1941

See more words from the same year

Keep scrolling for more

More Definitions for radar



English Language Learners Definition of radar

: a device that sends out radio waves for finding out the position and speed of a moving object (such as an airplane)


ra·dar | \ˈrā-ˌdär \

Kids Definition of radar

: a radio device for detecting the position of things in the distance and the direction of moving objects (as distant airplanes or ships)

Keep scrolling for more

Comments on radar

What made you want to look up radar? Please tell us where you read or heard it (including the quote, if possible).


required by fashion, etiquette, or custom

Get Word of the Day daily email!

Test Your Vocabulary

Great Scrabble Words—A Quiz

  • scrabble-tiles-that-read-scrabble-quiz
  • Which of the following Q-without-U words means the number five in cards or dice?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!