jacket : Sometimes used as another term for dust jacket, a protective and often decorative wrapper, usually made of paper which wraps around the binding of a book

Mass market paperback : Also known as the pocket paperback. A small format paperback usually measuring about 4" by 6".

8vo : Short for 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 folded and cut into 16 pages.. Unfortunately often misunderstood to mean 8 volumes.