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 Philippines dispatched the BRP Teresa Magbanua, one of its largest coast guard ships, to intercept the Chinese vessel, based on AIS location transponder data from both ships. —Micah McCartney, MSNBC Newsweek, 5 May 2025

The agency requires registrations for drones weighing more than 0.55 pounds, and such drones are required to carry a radio transponder that identifies the drone's owner and broadcasts its position to help avert collisions. —CBS News, 21 Apr. 2025

At the height of the action, when St. Crispin’s Day and her band of misfits deploy the semiotic transponder, a barrage of words that should arrive with a gut-flipping wallop hits more above the neck than below it. —Sara Holdren, Vulture, 23 Feb. 2025

How much guilt is your Misty carrying about breaking the airplane transponder, and is this now her moment of redemption? —Jackie Strause, HollywoodReporter, 17 Apr. 2025

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