# transponder

/tɹænˈspɑndɝ/ (US) · /tɹænspˈɒndɐ/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/transponder
Updated: 2026-05-09

## Definition

a piece of equipment that receives a radio signal and automatically sends a different signal back. You find these on planes and ships so that radar can identify them.

For teachers: an electronic device that emits a response upon receiving a specific radio-frequency interrogation signal. Commonly used in aviation and maritime contexts for identification and tracking.

## Examples

- The pilot turned on the transponder before takeoff.
- Air traffic control lost the aircraft's position on the screen after its transponder stopped transmitting.
- Modern satellite communications rely on multiple transponders to receive signals from Earth and retransmit them across a broad geographic area on different frequencies to avoid interference.

## Usage notes

- Often used in technical contexts involving telecommunications, aviation, or satellite technology.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.