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

The French detachment said the Russian planes didn’t have switched-on transponders, file flight plans or enter into radio contact. —ABC News, 24 Apr. 2026

The equipment did not provide a warning the night of the collision since the fire trucks did not have transponders and were only partially picked up by ground radar. —Aaron Cooper, CNN Money, 23 Apr. 2026

None of the ground vehicles were equipped with transponders, the report said. —Doha Madani, NBC news, 23 Apr. 2026

Drivers can pay via their Peach Pass or other eligible toll tag transponders. —Dan Raby, CBS News, 22 Apr. 2026

Word History

Etymology

transmitter + responder

First Known Use

circa 1944, in the meaning defined above

Rhymes for transponder

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