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

bumping : Indicates that the affected part of the book has been impacted in such a way so as to cause a flattening, indention, or light bending.

4to : Or quarto. A term used generally to describe the approximate size of a book, a book that is about 10" to 12" tall and roughly squarish in shape. The term is based on the size of paper traditionally used by book printers which has been folded and cut into 16 pages.