transponder

noun

tran·​spon·​der tran(t)-ˈspän-dər 

: 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

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

Lenovo’s response was to devise a system that used in-car transponders and a camera mounted above RCR’s pitbox to identify when a car has entered the box and begin a real-time videofeed. —Jason Barlow, WIRED, 14 Aug. 2024

The jets’ flight paths can be found on the website of ADS-B Exchange, which crowdsources location readings from airplane transponders. —Rob Davis, ProPublica, 13 Aug. 2024

Many of these ships turn off their locational transponders and cross secretly into Argentine waters. —Ian Urbina, Los Angeles Times, 4 Aug. 2024

Many of these companies have been tied to a variety of crimes, including dumping fish at sea, turning off their transponders, and engaging in tax evasion and fraud. —Ian Urbina, TIME, 1 Aug. 2024

Word History

Etymology

transmitter + responder

First Known Use

circa 1944, in the meaning defined above