decode

IPA/diːˈkəʊd/
KK[dɪkˈod]IPA/diːˈkəʊd/

decode — verb

  • decodepresent simple I / you / we / they
  • decodeshe / she / it
  • decodedpast simple
  • decoding-ing form

1. to turn a message that has been written using a secret set of symbols or letters

1.verbtransitiveB2
Definition

to turn a message that has been written using a secret set of symbols or letters back into ordinary text that can be easily read and understood.

Example

During the war, the team worked all night to decode the enemy's secret radio messages.

decode + noun phrase (radio messages)

Mei-Lin used the key she found in the old book to decode her great-aunt's coded diary entries.

Common collocations
  • decode a message
  • decode a code/cipher
  • decode signals
  • decode data
  • decode symbols
  • decode the meaning
Synonyms
  • decipher

    more about working out the meaning of something hard to read or understand, not necessarily in code; 'decode' is more technical

  • crack

    informal, suggests breaking a code or puzzle through effort; 'crack the code' is a fixed phrase

  • decrypt

    specifically about converting encrypted (scrambled) data back to original form using a key

Antonyms
  • encode

    to convert ordinary text into a secret code

  • encrypt

    to scramble data so that only authorised parties can read it

Grammar Patterns

decode + noun phrase (message/code/signal)

be decoded + into + noun phrase

Usage Note

Frequently used with 'encrypted', 'coded', or 'secret' before the object noun. The passive form is common when describing the message itself rather than the person decoding it: 'The message was decoded by the intelligence team.' Distinguish from sense 2 (foreign language) where no secret code is involved — the information is just in an unfamiliar language.

Common Mistakes

He decoded the Spanish poem on the first try.' (when he just read it in Spanish)
He translated the Spanish poem on the first try.
'decode' for foreign language sense (sense 2) implies active effort to work out meaning, not fluent reading.
The computer decoded the encrypted files into plain text.
The computer decrypted the encrypted files into plain text.
If the files were encrypted (not just encoded), 'decrypt' is more precise; 'decode' covers the conversion from code to readable form.

2. to work out the meaning of a foreign word or phrase by using the vocabulary and

2.verbtransitiveB2
Definition

to work out the meaning of a foreign word or phrase by using the vocabulary and grammar rules you have learned.

Example

Samira opened a translation app on her phone to decode the Korean street signs while travelling in Seoul.

to decode + noun phrase (Korean street signs) — foreign language context

The translator paused to decode the archaic French expression that appeared in the 18th-century letter.

Common collocations
  • decode a word/phrase
  • decode a language
  • decode a text
  • decode the meaning
  • decode what someone says
Synonyms
  • decipher

    broader — can mean working out any kind of unclear writing, not just a foreign language

  • make out

    phrasal verb, more informal; suggests straining to see or hear clearly

  • figure out

    informal; general problem-solving, not specific to language

Grammar Patterns

decode + noun phrase (word/phrase/language/text)

decode + what/how/why clause

Usage Note

Object is typically a foreign-language word, phrase, text, or expression you encounter while reading or listening. Unlike sense 1 (CRACK CODE), there is no deliberate secrecy — the difficulty comes from lack of fluency. Use 'translate' when the output is in the reader's own language; use 'decode' when the reader is still figuring out the basic meaning within the original language.

Common Mistakes

She decoded the French menu into English for her friend.
She translated the French menu into English for her friend.
'decode' keeps you inside the foreign language; 'translate' moves between languages.
He decoded the novel from cover to cover in one weekend.
He read the novel from cover to cover in one weekend.
if you understood it fluently without effort, 'decode' is the wrong word.

3. to change a stream of electronic information into a form that a computer, televi

3.verbtransitiveB2
Definition

to change a stream of electronic information into a form that a computer, television, or other device can use, such as sounds, pictures, or readable text.

Example

The set-top box decodes the digital television signal and shows the programme on the screen.

technical object: digital television signal

Kenji installed a new software library that can decode video files from the office security cameras.

Common collocations
  • decode a signal
  • decode data
  • decode a broadcast
  • decode an audio stream
  • decode a video file
  • decode digital television
Synonyms
  • convert

    more general; 'decode' implies reversing an encoding process

  • interpret

    less technical; can suggest making sense of raw data

  • demodulate

    highly technical; the electronic process of extracting a signal from a carrier wave

Antonyms
  • encode

    to convert audio/video data into a format suitable for transmission or storage

  • compress

    to reduce file size, often part of the encoding process

Grammar Patterns

decode + noun phrase (signal/data/broadcast/stream)

be decoded + into + noun phrase

decode + audio/video/digital + noun phrase

Usage Note

Subject is often a device, software, or system rather than a person. The object is almost always a technical signal type (digital signal, video stream, audio data, broadcast, transmission). The antonym in this sense is 'encode' — converting a signal into a transmittable form. Do not confuse with 'decrypt', which specifically refers to reversing encryption (scrambling that requires a key).

Common Mistakes

This phone cannot decode the encrypted photo.
This phone cannot decrypt the encrypted photo.
If the data was encrypted (scrambled for security), use 'decrypt'. 'Decode' applies when the signal is merely compressed or formatted, not scrambled.
The old radio cannot decode the pirate broadcast.
The old radio cannot receive the pirate broadcast.
'decode' is about signal format conversion, not about picking up a transmission.

Word family

Synonym discussion

Sense: verb/1

All four words involve extracting meaning from something that is not immediately readable, but they differ in scope and register. 'Decode' is the most general: it means converting a coded or formatted message into a readable form, whether that code is a simple letter substitution, a digital encoding, or a foreign language. 'Decipher' overlaps with 'decode' but places more emphasis on slowly working out something hard to read — it can refer to messy handwriting or obscure symbols, not just formal codes. 'Decrypt' is narrower and more technical: it specifically means reversing cryptographic encryption, which requires a key or algorithm to unscramble data that was deliberately scrambled for security. 'Crack' is informal and often implies solving a puzzle or breaching a security system through clever effort ('crack the code', 'crack the password'). For example, a historian deciphers faded handwriting, a security engineer decrypts a stolen file, and a puzzle enthusiast decodes a cryptogram in a magazine. A teenager who cracks the Wi-Fi password is doing something closer to 'decrypt' but with an informal, playful tone.

decode ↗decipher ↗decryptcrack ↗

Common collocations

Nouns

Adverbs

Phrases

  • in order to decode
  • by decoding
  • able to decode
  • unable to decode

Prepositions

Etymology

LatinFrenchEnglish

'Decode' was formed in English around the 1890s by adding the prefix 'de-' (meaning 'reverse' or 'remove') to the noun 'code'. 'Code' itself comes from Old French 'code', which was taken from Latin 'codex' — originally a block of wood for writing on, later a book of laws or systematic rules. The word first appeared in telegraph and military contexts, where messages were sent in code to save time or maintain secrecy. The computing and electronics senses emerged in the mid-20th century as digital technology developed.