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. [Written also jagg.]

Jagging iron, a wheel with a zigzag or jagged edge for cutting cakes or pastry into ornamental figures.

Source: Webster's Revised Unabridged Dictionary (1913)