The crossword solution for the term BOOK SPACE is RENT, which is a four-letter word. Renting a book space is a common practice in libraries and bookstores, where customers can borrow books for a certain period of time. It is also possible to RENT out book spaces for private use, such as for a study or reading room. Renting a book space can be a cost-effective way to access a wide range of books without having to purchase them.