tran·​spon·​der tran(t)-ˈspän-dər How to pronounce transponder (audio)
: 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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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 One way to keep track of where planes are is a transponder, which sends out a signal announcing the aircraft’s location. Kelsey D. Atherton, Popular Science, 17 Aug. 2023 The transponder showing its location then went dark, according to Mr. Salzman, and did not come back on until four days later, near the same spot. Lynsey Chutel, New York Times, 3 Sep. 2023 The grace period for pet owners to tag their animals with a passive integrated transponder tag and then register them with the Georgia Department of Natural Resources ends at midnight on Dec. 3, the agency said. Gina Martinez, CBS News, 2 Nov. 2023 Producers of Parmigiano-Reggiano have started embedding edible microchip transponders in their cheese to mark them as authentic, giving a whole new meaning to chips and queso. Laura Reiley, Washington Post, 12 Oct. 2023 Cars traveling in the pair of express lanes are no longer required to obtain a FasTrak transponder. Brennon Dixson, Los Angeles Times, 23 June 2023 On northwest Orange County’s new express lanes, cars are required to use a FasTrak transponder, which can be purchased online. Grace Toohey, Los Angeles Times, 1 Dec. 2023 Then its transponder stopped transmitting its signal. Terrence McCoy, Washington Post, 23 Oct. 2023 Using a laser for excitation gives the p-Chip a couple of advantages over other transponders, says Ioannis Kymissis, a professor of electrical engineering at Columbia University. IEEE Spectrum, 8 Sep. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'transponder.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


transmitter + responder

First Known Use

circa 1944, in the meaning defined above

Time Traveler
The first known use of transponder was circa 1944

Dictionary Entries Near transponder

Cite this Entry

“Transponder.” Dictionary, Merriam-Webster, Accessed 3 Mar. 2024.

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