The word "清单" is formed by combining two meaningful characters: "清" (qīng), which carries the core idea of "clear", "distinct", or "tidy", and "单" (dān), which means "list", "sheet", or "bill". The formation is conceptual, where the first character "清" describes the quality or state of the second character "单". Together, they create a compound meaning a "clear list" or an "itemized sheet", where the clarity refers to the list's well-organized, unambiguous, and easy-to-read nature.