The Collaborative International Dictionary
Jagging iron
Jag \Jag\, v. t. [imp. & p. p. Jagged; p. pr. & vb. n. Jagging.] To cut into notches or teeth like those of a saw; to notch.
Jagging iron, a wheel with a zigzag or jagged edge for cutting cakes or pastry into ornamental figures.
Wiktionary
jagging iron
n. A wheel with a zigzag or jagged edge for cutting cakes or pastry into ornamental figures.