A code is a system of replacing the words in a message with other words or symbols, so that nobody can understand it unless they know the system.
A code is a system of words, letters, or signs used to represent a message in secret form, or a system of numbers, letters, or signals used to represent something in a shorter or more convenient form: The message was written in code
A code is a system of replacing the words in a message with other words or symbols, so that nobody can understand it unless they know the system.
A code is a system of words, letters, or signs used to represent a message in secret form, or a system of numbers, letters, or signals used to represent something in a shorter or more convenient form: The message was written in code