plural transponders
: a wireless device (such as an RFID microchip or radio) 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The United States is currently managing to get significant amounts of crude oil (if not refined product) through the strait, but only by providing costly military protection to tankers that slip past Iran’s guns with their transponders off. — Philip H. Gordon, Foreign Affairs, 12 Oct. 2026 Shortly after, an emergency transponder beacon was detected on radar near the Eldorado Springs area of Boulder County. — Jennifer McRae, CBS News, 6 Oct. 2026 While the Coast Guard did not provide details on those tactics, ships can hide their destination through various means, including turning off their location transponders and going dark. — David C. Adams, New York Times, 2 Oct. 2026 The unit combines interrogation and transponder functions in a single box. — Aamir Khollam, Interesting Engineering, 29 Sep. 2026 See All Example Sentences for transponder

Word History

Etymology

transmitter + responder

First Known Use

circa 1945, in the meaning defined above

Time Traveler
The first known use of transponder was circa 1945

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Cite this Entry

“Transponder.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/transponder. Accessed 20 Oct. 2026.

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