The term "commonplace book" comes from the latin phrase locus communis, which itself is from the greek τόπος κοινός (tópos koinós), meaning "general topic", or "an idea applicable to many particular cases" - a gathering of ideas in various forms that are applicable, if not universally, at least outside their original context, and organized so as to encourage exploration of their relation one with another, and broader applications.
I use this page as a memex, an interconnected section of notes. Some of them are rough drafts, and all of them are prone to change.