ETYM French, from Latin codex, caudex, the stock or stem of a tree, a board or tablet of wood smeared over with wax, on which the ancients originally wrote; hence, a book, a writing.
1. A set of rules or principles or laws especially written ones; SYN. codification.
2. A coding system used for transmitting messages requiring brevity or secrecy.
3. (Computer science) The symbolic arrangement of data or instructions in a computer program or the set of such instructions; SYN. computer code.
In law, the body of a country’s civil or criminal law. The Code Napoléon in France 1804–10 was widely copied in European countries with civil law systems.

To attach a code to.

1. Program instructions. Source code consists of human-readable statements written by a programmer in a programming language. Machine code consists of numerical instructions that the computer can recognize and execute and that were converted from source code. See also data, program.
2. A system of symbols used to convert information from one form to another. A code for converting information in order to conceal it is often called a cipher.
3. One of a set of symbols used to represent information.

To write program instructions in a programming language. See also program.