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 company reported a net revenue of $26.6 million for 2024, a decrease from $43.4 million in 2023, attributed to lower unit sales of RFID transponder products. —Quartz Intelligence Newsroom, Quartz, 17 Mar. 2025

The Federal Aviation Administration (FAA) maintains a database of aircraft registration and flight data, and tools to track flights using publicly accessible transponder data. —David Faris, Newsweek, 17 Mar. 2025

Both aircraft had functioning lights and transponders before impact, suggesting that visibility was not a primary issue. —Kathleen Wong, USA TODAY, 11 Mar. 2025

In the ship-tracking database, both Xing Shun 39 and Shun Xing 39 identify themselves as cargo ships with a class A AIS transponder. —Meaghan Tobin, New York Times, 7 Jan. 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