In historic book production, printers placed this isolated word below the final line of text on a page. It served as a vital guide for bookbinders to ensure they folded and gathered the printed sheets in the correct sequence. While originally functional for collation, it also provided readers with a visual bridge to the next page before turning the leaf.
The binder got the sequence wrong because the catchword on page 16 was completely obscured by a heavy ink smudge.
Related terms
Signature
A large printed sheet folded multiple times to form a sequential section of a book.
Recto
The right-hand page of an open book or manuscript, traditionally bearing an odd page number.
Verso
The left-hand page of an open book or manuscript, traditionally carrying an even page number.
Colophon
A publisher or printer's emblem or production note placed inside a book.