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

For example, maritime intelligence group Windward said six Iranian VLCCs, or very large crude carriers, were on Friday operating with their transponders off or broadcasting deceptive locations while at Kharg. —Tim Lister, CNN Money, 16 Mar. 2026

Smith says nine Iranian oil tankers have traveled through the Strait of Hormuz by turning off transponders that reveal locations. —Cecilia Vega, CBS News, 15 Mar. 2026

Destination signals are short notes or messages manually entered by a ship's crew into a vessel's transponder, a global positioning system locator, and broadcast publicly, Subasic said. —ABC News, 12 Mar. 2026

Iran, however, is successfully exporting its oil, largely via its shadow fleet of ships that turn off their transponders. —Jim Edwards, Fortune, 12 Mar. 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