Etymology

Noun

1. A very short abbreviation, often with little correlation to the item it represents

   You assigned the same "unique" code to two intake-categories, causing a database error!

2. A body of law, sanctioned by legislation, in which the rules of law to be specifically applied by the courts are set forth in systematic form; a compilation of laws by public authority; a digest.

   "The collection of laws made by the order of Justinian is sometimes called, by way of eminence, "The Code"." -Wharton

3. Any system of principles, rules or regulations relating to one subject; as, the medical code, a system of rules for the regulation of the professional conduct of physicians; the naval code, a system of rules for making communications at sea means of signals.
4. A set of rules for converting information into another form or representation.
5. A cryptographic system using a codebook that converts words or phrases into codewords.
6. Source code.
7. A computer program, or more generally, any defined computing process.

Verb

1. To write software programs.
2. To categorise by assigning identifiers from a schedule, for example CPT coding for medical insurance purposes.
3. To encode.

   We should code the messages we sent out on usenet.