substitution cipher

noun

, Cryptography.

1. a cipher that replaces letters of the plain text with another set of letters or symbols.

Word History and Origins

Origin of substitution cipher¹

First recorded in 1935–40

Example Sentences

But a simple substitution cipher is easy to crack because certain letters, such as “e,” appear much more often than others.

From Scientific American

The “unbreakable” Pletts Cryptograph relied in part on keyword ciphers, a type of substitution cipher.

From Literature

In a substitution cipher, each letter of the message you want to send is swapped out for a different letter.

From Literature

This is a simple substitution cipher.

From Literature

Unlike a substitution cipher, it doesn’t replace any of the letters in the original message.

From Literature