decoder
nounUK /diːˈkəʊdə/
US /diːˈkoʊdər/
A decoder is a thing that changes a secret code into words you can understand.
The spy used a decoder to read the secret message.
OTHER MEANINGS
2. An electronic device that converts a coded signal into a form that can be seen or heard, such as in television or radio.
The cable box includes a decoder that turns the signal into a clear picture.
3. A program or part of a computer system that converts encoded data back into its original form.
The software uses a decoder to turn the compressed video back into a playable movie.
4. A person who figures out the meaning of something difficult or unclear.
She was a skilled decoder of her boss's vague instructions.