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.

cocked : Refers to a state where the spine of a book is lightly "twisted" in such a way that the front and rear boards of a book do not align when the book is lying flat. Severity may differ.

shaken : A hardcover in which the text block is loose, but still attached to the binding.