cipher

(noun): A numeric character.
(noun): Any text character.
(noun): A combination or interweaving of letters, as the initials of a name; a device; a monogram.
(noun): A method of transforming a text in order to conceal its meaning.
(noun): A cryptographic system using an algorithm that converts letters or sequences of bits into ciphertext.
(noun): Ciphertext; a message concealed via a cipher.
(noun): A grouping of three digits in a number, especially when delimited by commas or periods:
(noun): A fault in an organ valve which causes a pipe to sound continuously without the key having been pressed.
(noun): A hip-hop jam session.
(noun): The path (usually circular) shared cannabis takes through a group, an occasion of cannabis smoking.
(noun): Someone or something of no importance.
(noun): Zero.
(verb): To calculate.
(verb): To write in code or cipher.
(verb): Of an organ pipe: to sound independent of the organ.
(verb): To decipher.

a painter's cipher, an engraver's cipher, etc.
The message was written in a simple cipher. Anyone could figure it out.
The message is clearly a cipher, but I can't figure it out.
The probability is 1 in 1,000,000,000,000,000 — a number having five ciphers of zeros.
I never learned much more than how to read and cipher.