means Having a rough, uneven edge or outline marked by sharp points and notches rather than a smooth surface.

from From Middle English 'jaggen,' meaning to pierce, slash, or cut into notches — the same impulse that gave us 'jag,' a sharp projecting point. The word is likely imitative or expressive in origin, its very sound suggesting something catching and tearing, and by the late Middle Ages a 'jagged' cloak meant one deliberately slashed at the edges, a fashion of ornamental raggedness.