boards : Common term for the covers of a hardbound book.

octavo : A book whose page size is approximately 12 inches by 9 inches. The size is based on a sheet of paper 25 inches by 38 inches, the size of paper traditionally used by book printers, which has been cut into eight pages.

spine : The outer portion of a book which covers the actual binding. The spine usually faces outward when a book is placed on a shelf. Also known as the back.