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

DJ : Short for dust jacket, a protective and often decorative wrapper, usually made of paper which wraps around the binding of a book.

8vo : Short for Octavo, A book whose page size is approximately 8-10 inches tall. 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 folded and cut into 16 pages.. Unfortunately often misunderstood to mean 8 volumes.