"What is books" can be rephrased in various ways using synonyms. For example, "what are printed works," "what comprises literature," "what constitutes written material," or "what encompasses the collection of narratives." When referring to a specific category, one can say "what are novels," "what are textbooks," or "what are biographies." Additionally, the term "books" can be swapped with different phrases such as "written resources," "bound volumes," or "printed publications" to modify the statement. Overall, there are multiple ways to phrase the question "what is books" depending on the context and intended meaning.