substitution cipher

noun

UK /ˌsʌbstɪˈtjuːʃən ˈsaɪfə/

US /ˌsʌbstɪˈtuːʃən ˈsaɪfər/

A secret code where you swap each letter for a different letter.

In the substitution cipher, every A became a D, so the message looked like gibberish.

SYNONYMS

letter-swap code replacement cipher simple cipher secret code

RELATED WORDS

encryption cryptography cipher key decoder plaintext

OTHER MEANINGS

2. A method of hiding a message by replacing each symbol with another symbol according to a fixed rule.

The spy used a substitution cipher to keep the plan secret.

3. A puzzle technique where one letter consistently stands for another throughout the text.

Solving the substitution cipher took hours because the same letter always meant the same thing.

4. Any coding system in which units of plaintext are replaced by ciphertext units.

Historians studied the ancient substitution cipher carved on the stone.