The work — or the finished result — of putting a pile of rules into one clear system. Lawyers talk about the codification of the law when a country gathers old customs and court decisions and writes them as a neat set of statutes you can open and point to. Teachers and scientists stretch it a little: any tidy listing of principles can be called a codification. It is a formal, academic word. You feel it in law school more than in daily talk. It is the noun that sits beside the verb codify. In computer class “coding” means writing programs; that is a different use of the old “code” family, though actually the two sit side by side in a student’s notebook and get swapped.