The word **书籍 (shūjí)** is a compound noun formed by combining two synonymous characters, each meaning "book" or "written work," to create a single, more formal and collective term. The first character, **书 (shū)**, broadly means "book" or "to write," while the second, **籍 (jí)**, historically referred to bound bamboo-slip manuscripts or registers, carrying connotations of records and volumes. When paired, they reinforce each other to denote "books" in a general, literary sense, often implying a collection or the concept of published works as a whole, making it more abstract and formal than the standalone word **书**.