tran·​spon·​der | \ tran(t)-ˈspän-dər How to pronounce transponder (audio) \

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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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 The new rates will range from $2.40 per trip for a vehicle with a transponder to $14.38 for a five-axle vehicle paying by mail. Krista Johnson, The Courier-Journal, 22 June 2022 The color scale of aircraft traffic is based on the number of aircraft that sent transponder locations originating from that spot. David Yanofsky, Quartz, 16 June 2022 With a calm voice, the air traffic controller at Treasure Coast International Airport in Florida instructed the passenger how to use his transponder so the aircraft could be located via radar. Nathan Solis, Los Angeles Times, 11 May 2022 Founder Dan Streufert said pretty much any plane flying around the globe has a transponder that broadcasts the plane’s unique ID and its position, for safety reasons such as avoiding collisions. Washington Post, 7 Mar. 2022 But while Anik F1R still had its uplink license and transponder slot lease, Koscher had the opportunity to take over and broadcast to the northern hemisphere. Lily Hay Newman, Wired, 30 Mar. 2022 Many of the unpaid tolls accrued between March 2020 and October 2020, when the Maryland Transportation Authority continued to charge tolls but did not mail bills for vehicles without an E-ZPass transponder, the authority said. Washington Post, 24 Feb. 2022 Visitors who have a LeeWay, SunPass or other transponder (including E-ZPass) are assessed a $6 fee. Susan Glaser, cleveland, 20 Jan. 2022 Drivers use a SunPass transponder to pay to drive in the express lanes; the cost ranges from 50 cents to an estimated $10.50, depending on the time of day, the amount of traffic and distance traveled in the express lanes. Lois K. Solomon,, 13 Jan. 2022 See More

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.

First Known Use of transponder

circa 1944, in the meaning defined above

History and Etymology for transponder

transmitter + responder

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Time Traveler for transponder

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The first known use of transponder was circa 1944

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Last Updated

20 Jul 2022

Cite this Entry

“Transponder.” Dictionary, Merriam-Webster, Accessed 11 Aug. 2022.

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More from Merriam-Webster on transponder

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


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