From Longman Dictionary of Contemporary Englishtranspondertrans‧pond‧er /trænˈspɒndə $ -ˈspɑːndər/ noun [countable] technicalTC a piece of radio or radar equipment that sends out a signal when it receives a signal telling it to do this
Examples from the Corpus
transponder• This system would require the fitment of special electronic transponders to each bus in order to alert traffic signals.• The product is the result of an agreement signed in October 1991 for joint development of an FRAM-compatible radio frequency transponder chip.• A malfunctioning transponder would leave dots on the radar tape, not a streak, according to the manual, Schulze said.• I'd just squawked the new transponder code when I saw a helicopter ahead at two o'clock.• On Standby the transponder unit is on, but does not give a response.• Alvin is recovered first, and then the ship is brought into position to pick up the transponder.• The transponder was released acoustically just after Alvin left the bottom for the last time in this area.Origin transponder (1900-2000) transmitter + responder 