The ornamental design for a cutterknife, as shown and described.
1.-2. Cutter knife
1.1 : Top perspective view
1.2 : Bottom perspective view
1.3 : Front view
1.4 : Left view
1.5 : Right view
1.6 : Top view
1.7 : Bottom view
2.1 : Top perspective view
2.2 : Bottom perspective view
2.3 : Front view
2.4 : Left view
2.5 : Right view
2.6 : Top view
2.7 : Bottom view
The part represented by solid lines is the claimed-design, and other parts represented by broken lines form no parts of the claimed-design; in designs 1 and 2 the back view is the mirror image of the front view.