tran·​spon·​der | \tran(t)-ˈspän-dər \

Definition of transponder 

: a radio or radar set that upon receiving a designated signal emits a radio signal of its own and that is used especially for the detection, identification, and location of objects and in satellites for relaying communications signals

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Did You Know?

This word was coined during World War II by simply joining pieces of the words transmitter and responder. Transponders are basic to modern aviation and communications satellites, and they're finding new uses in fields such as medicine as well. But they're now also part of everyday life. The "E-ZPass" that lets you drive right through turnpike tollbooths is a transponder, and the car you're driving may not even start unless it recognizes the signal from your personal key's transponder. In a big crowded foot race, you may carry a tiny transponder on your shoe that records when you cross both the starting line and the finish line.

Examples of transponder in a Sentence

Recent Examples on the Web

There is no indication of its whereabouts until Aug. 17, when its transponder signal reappears at Nahodka, a port about 100 miles from Vladivostok in Russia’s Far East, the data shows. Joby Warrick, Washington Post, "High seas shell game: How a North Korean shipping ruse makes a mockery of sanctions," 3 Mar. 2018 Es’hail-2 has two transponders on board that can connect to amateur radios from South America to Asia. Loren Grush, The Verge, "Watch SpaceX launch and land a used Falcon 9 rocket," 15 Nov. 2018 During the transition, SunPass transponders were still recognized and tolls were still charged, but drivers were being advised to replenish their accounts before the shutdown. Wayne K. Roustan,, "Revamped SunPass system sluggish after a stumbling start," 13 June 2018 SunPass transponders will hold transactions during the maintenance period and submit afterward at the Orlando Airport. Howard Cohen, miamiherald, "Use SunPass? You may be in for a week-long headache when the system undergoes maintenance," 30 May 2018 According to reports, the pilot accidentally entered a hijack alert in the plane’s transponder, which is used to indicate an emergency. Natasha Bach, Fortune, "A JetBlue Pilot Accidentally Triggered a Hijacking Alert. Panic and Chaos Ensued," 27 June 2018 For drivers who don’t have a SunPass transponder, they are charged via their pay-by-plate. Johnny Diaz,, "Miami driver dodges Sunpass toll with hide-and-seek license plate," 21 June 2018 The authority will verify a driver’s account of the cause and location of damage, including through toll-transponder data. Kevin Spear,, "I-4 construction nightmares: Drivers seeking payment for car damage face daunting odds," 13 July 2018 About 4 million of those each month do not have transponders. Adam Vaccaro,, "1.3 million cars have slipped through Mass. toll gantries," 24 May 2018

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

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First Known Use of transponder

circa 1944, in the meaning defined above

History and Etymology for transponder

transmitter + responder

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Last Updated

13 Dec 2018

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Time Traveler for transponder

The first known use of transponder was circa 1944

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English Language Learners Definition of transponder

: a device that receives a radio signal and sends out a signal in response and that is used especially to show the location of something (such as an airplane)

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More from Merriam-Webster on transponder

Rhyming Dictionary: Words that rhyme with transponder

Nglish: Translation of transponder for Spanish Speakers Encyclopedia article about transponder

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to make faulty or ineffective

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