: a book back in which the backs of the sections are affixed to the backbone of the cover only at the joints, the separation sometimes being made by a flattened tubular lining of paper or cloth; also : a book so bound or a style of binding featuring this construction — called also open back, spring back; compare tight backbone; see spine illustration
* * *
—hollow-backed, adj.
Bookbinding.
a paper tube or roll, almost flattened, having one side glued to the back of a book and the other to the inside of the spine.
Useful english dictionary. 2012.