Metal, wooden, bone, ivory or plastic knife (approx. 20-25 cm long), usually in one piece, with a flat and narrow (approx. 0.5-1 cm) blade that tapers towards the end. The edge is not sharp and the point is relatively blunt. With a paperknife you can easily cut open envelopes and books; it is inserted respectively into the fold of the cover or between two uncut leaves of a book and then cut open along the fold.
Sometimes the letter opener is equipped with a pocket knife at the other end.
Another paperknife model has a razor-sharp blade (approx. 3 cm) in a rectangular plastic handle, which is no thicker than 4 mm.
This type of paperknife is not to be confused with the folder. [MOT]