transponder

noun

tran·​spon·​der tran(t)-ˈspän-dər 

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

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

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

In September 2025, Mastercard, Volvo Cars and the North Carolina Turnpike Authority launched a pilot program that lets drivers pay tolls directly from the vehicle, using GPS positioning and tokenized payment credentials in place of a transponder. — Stacey Moser, Forbes.com, 25 Sep. 2026

The high-speed lanes were equipped with transponder readers that could deduct tolls from drivers with in-car toll passes as well as license tag readers that could charge tolls to vehicles without transponders, NTSB investigators noted. — Aaron Cooper, CNN Money, 18 Sep. 2026

Word History

Etymology

transmitter + responder

First Known Use

circa 1945, in the meaning defined above

Rhymes for transponder

• responder
• condor
• fonder
• launder
• mandir
• maunder
• ponder
• squander
• wander
• yonder