All 18 Uses of

cipher
in
The Da Vinci Code

Part of it looks like a numeric cipher.
Chpt 8

cipher = something written in a secret code

At the age of twelve, Sophie could finish the Le Monde crossword without any help, and her grandfather graduated her to crosswords in English, mathematical puzzles, and substitution ciphers.
Chpt 15-16

ciphers = substitution tables or other systems used to encode and decode messages so those who don't know the system can't understand the messages

Langdon had once worked on a series of Baconian manuscripts that contained epigraphical ciphers in which certain lines of code were clues as to how to decipher the other lines.
Chpt 19-20

ciphers = keys to encode and decode something

Mary, Queen of Scots created a transposition cipher and sent secret communiqués from prison;
Chpt 47-48

cipher = system to encode and decode messages so those who don't know the system can't understand the messages

...and the brilliant Arab scientist Abu Yusuf Ismail al-Kindi protected his secrets with an ingeniously conceived polyalphabetic substitution cipher.
Chpt 47-48

The Atbash Cipher had indeed been part of Sophie's early cryptology training.
Chpt 71-72

The cipher dated back to 500 B.C. and was now used as a classroom example of a basic rotational substitution scheme.
Chpt 71-72

A common form of Jewish cryptogram, the Atbash Cipher was a simple substitution code based on the twenty-two-letter Hebrew alphabet.
Chpt 71-72

The Priory certainly would include the Atbash Cipher as part of their teachings.
Chpt 71-72

"The only problem," Langdon said, "is that we don't have anything on which to apply the cipher."
Chpt 71-72

It works for all reflectional substitution ciphers, including the Atbash.
Chpt 77-78

ciphers = systems to encode and decode messages so those who don't know the system can't read the messages

Looking at Sophie's substitution matrix, Langdon felt a rising thrill that he imagined must have rivaled the thrill felt by early scholars when they first used the Atbash Cipher to decrypt the now famous Mystery of Sheshach.
Chpt 77-78

cipher = system to encode and decode messages so those who don't know the system can't understand the messages

Finally, a scholar applied the Atbash Cipher to the word, and his results were mind-numbing.
Chpt 77-78

The cipher revealed that Sheshach was in fact a code word for another very well-known city.
Chpt 77-78

Each block was carved with a symbol, seemingly at random, creating a cipher of unfathomable proportion.
Chpt 103-104

Definitions:

(1) (cipher as in: a secret cipher)
to write a message in a secret code; or such a message; or a substitution table or other system used to encode and decode such a message
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

At one time, cipher frequently referenced the act of doing mathematical calculations or a person capable of such calculations.

A cipher can also refer to a person without power or influence. It can also refer to the mathematical digit, zero.

A comprehensive dictionary will describe other less common senses of cipher.