A book that's been rebacked has been given a new spine or backstrip and had loose hinges mended.
The book's spine has been newly recovered.
The book has had a new spine attached at the hinges.
the spine has been replaced with new material.
A method of repair done to the spine, and usually the joints/hinges. When possible the original spine is saved and glued over the repaired one.
A repair, where the original spine or backstrip has been removed, the spine replaced, and the original reglued on top. Can be considered a defect, but more valuable than not having any of the original spine present.
the spine of the volume has been replaced, sometimes retaining portions of the original spine or the original title-label.
A book that has been repaired by getting a new spine and mended hinges.