(Bookbinding) One or more separate leaves inserted in a volume before binding; as:
(a)
A portion of the printed sheet in certain sizes of books which is cut off before folding, and set into the middle of the folded sheet to complete the succession of paging; also called offcut.
... Often he used inset illustrations, not so much to give point to his preachments, as to render them easier of comprehension to the unthinking. And always he sought the utmost of sensationalism in caption and in type, employing italics, capitals, and even heavy-face letters with ... — Success - A Novel • Samuel Hopkins Adams