Transponder

How to spell transponder

11 letters · 3 syllables

How to pronounce transponder

Say the part in capitals loudest.

What does transponder mean?

1. nounAn electronic device that receives a radio or radar signal and automatically transmits a coded reply, used for identification, tracking, or toll collection.

Transponder in a sentence

• Air traffic control could not see the small plane because its transponder had failed.

• A toll-road transponder mounted on the windscreen lets the car pass without stopping to pay.

Where does transponder come from?

Language of origin: Latin

Transponder is a twentieth century coinage, a portmanteau stitched together from 'transmitter' and 'responder'. It was minted in the 1940s, during and just after the Second World War, when radar and radio identification systems needed a device that would automatically send a reply the instant it received an incoming signal. The 'responder' half carries the older Latin verb respondere, meaning 'to answer' or 'to reply', built from re- 'back' and spondere 'to pledge or promise', so the original sense is of pledging something in return. The 'transmitter' half ultimately rests on the Latin transmittere, 'to send across', from trans- 'across' and mittere 'to send'. Because the modern word is a deliberate fusion rather than a natural descendant, the spelling fault line falls in the middle: writers tend to drop the 's' or muddle the 'pon' that bridges the two source words.

How the word is built

• trans(mitter)
• (re)sponder; a blend of transmitter and responder, where responder traces to Latin respondere 'to answer' (re- 'back'
• spondere 'to pledge'), plus the agent suffix -er