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

Like many ships using this new tactic, the Kiku reappeared a day after its transponder turned off while anchored near the Emirati port city of Fujairah. — David Goldman, CNN Money, 22 Aug. 2026

On Wednesday, nine commercial vessels with active Automatic Identification System (AIS) transponders transited the waterway, unchanged ​from Tuesday, data from Kpler ​showed. — Glenn Taylor, Footwear News, 20 Aug. 2026

Rasmussen in 1978 was idling in traffic on Connecticut’s Interstate 84 after acquiring a satellite transponder from RCA, and decided to launch a new network devoted only to sports on a single acre near the small town of Bristol. — Brian Steinberg, Variety, 18 Aug. 2026

The Secretary added that his numbers also include tankers which had transited the Strait of Hormuz with their lights and transponders turned off, keeping them hidden from the Iranian Revolutionary Guard Corps (IRGC) and tracking satellites. — David Blackmon, Forbes.com, 12 Aug. 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