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noun B2 Upper-Intermediate Common

radar

RAY-dah

Radar (noun) means a system that detects and tracks objects by sending out radio waves and analyzing the signals that bounce back. Example: “Air traffic controllers use radar to track planes approaching the airport.”

noun
1
A system that detects and tracks objects by sending out radio waves and analyzing the signals that bounce back.
"Air traffic controllers use radar to track planes approaching the airport."
2
An informal, figurative sense: someone's awareness or instinct for noticing something.
"His radar for bad business deals kicked in immediately."
"The new hire is talented but flew under management's radar for months."

How to use radar

Learner’s notes

In plain EnglishA detection system using radio waves, or informally, a sharp instinct for spotting something.

Common mistake

Since "radar" began life as an acronym, it doesn't need capital letters in modern writing.

Easily confused with
Common pairings
on the radar under the radar radar screen fly under the radar

Word forms

radared past tense, radars plural, radars singular

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Fill the gap

Can you complete this real example?

Air traffic controllers use _____ to track planes approaching the airport.

Etymology

Originally an acronym for "radio detection and ranging", coined by US Navy officers in 1940; it later became an ordinary word in its own right.

· First attested 1940

Class of 1940 radar joined the language around 1940.
See the full Class of 1940 →
radiolocation microwave radar radio detection and ranging

Related words

Frequently asked questions

What does “radar” mean?

The word “radar” means a system that detects and tracks objects by sending out radio waves and analyzing the signals that bounce back. In plain terms, a detection system using radio waves, or informally, a sharp instinct for spotting something.

How do you pronounce “radar”?

“Radar” is pronounced RAY-dah (/ˈɹeɪˌdɑɹ/ in IPA).

How do you use “radar” in a sentence?

Here is “radar” used in a sentence: “Air traffic controllers use radar to track planes approaching the airport.”

What part of speech is “radar”?

“Radar” is a noun.

Where does the word “radar” come from?

The word “radar” dates back to around 1940. Originally an acronym for "radio detection and ranging", coined by US Navy officers in 1940; it later became an ordinary word in its own right.

Is “radar” a common word?

“Radar” is a fairly common word in modern English, usually learned at around the B2 level.

How many meanings does “radar” have?

“Radar” has 2 distinct senses listed in this dictionary. The most common is: a system that detects and tracks objects by sending out radio waves and analyzing the signals that bounce back.

What does the word "radar" stand for?

"Radar" is an acronym for "radio detection and ranging." It describes a system that detects and tracks objects by sending out radio waves and analysing the signals that bounce back.

What is the difference between "radar" and "sonar"?

"Radar" detects and tracks objects using radio waves, and is used mainly in the air and on land. "Sonar" does a similar job using sound waves and is used underwater, so the two systems suit different environments.

Is "radar" written in capitals?

Although "radar" began as an acronym, it is now treated as an ordinary word and written in lowercase in normal use. You only capitalise it at the start of a sentence, unlike acronyms that are still written in full capitals.

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