Creaser

noun

1. A tool having a thin triangular head, used to crease leather.
2. A tool for creasing or crimping cartridge-cases.
3. In bookbinding, a tool which creases and sharply defines the width of the bands of books, and fixes the position of lines on the backs and sides, the lines being afterward covered by a blind roll or blind stamp.
4. An attachment to a sewing-machine for making a crease to serve as a guide for the next row of stitching.
5. A tool, or a sewing-machine attachment, for making lines or creases on leather or cloth, as guides to sew by.