letter-substitution code
nounUK /ˈletə ˌsʌbstɪˈtjuːʃən kəʊd/
US /ˈletər ˌsʌbstɪˈtuːʃən koʊd/
A letter-substitution code is a secret way to write where you swap each letter for a different one.
The spy used a letter-substitution code to hide the message from his friends.
RELATED WORDS
OTHER MEANINGS
2. A puzzle where you figure out which letter stands for which.
We solved the letter-substitution code in the newspaper together.
3. A method of hiding words by changing letters in a pattern.
The class made a letter-substitution code using the key A=B, B=C.
4. A simple kind of secret writing used in games and stories.
In the treasure hunt, each clue was written in a letter-substitution code.