The process of creating backing joints usually to accommodate the boards of a book. Backing joints can come in a variety of shapes (quadrant, slight, square, angled). The process of backing can be carried out either by lacing the boards on tightly and pulling them shut or by means of a backing hammer applied to a bookblock locked up in a press.
Roberts, Matt, Don Etherington, and Margaret R. Brown. 1982. Bookbinding and the conservation of books: a dictionary of descriptive terminology. Washington: Library of Congress.
The Arts and Architecture Thesaurus Online, The Getty Research Institute.