Has been called a bibiolot, when in fact, it should have been called a bibioless. Each of these sizes has several variations within the size. An inexact science at best and hardly worth the discussion. Spine or back strip . The back of the book.
Tips are the top and bottom of the spine.
Tipped-in plates . Often on higher quality, illustrated books, the plates are printed separately on a better grade of paper and glued lightly along one edge to a blank page. After the gatherings are sewn or glued together, the publisher may or may not want to trim the fore edge of the pages. If they are left uncut, it leaves a rather ragged, romantic look. If trimmed, it looks like most other books.