Definitions of jag:

• noun:   a bout of drinking or drug taking
• noun:   a flap along the edge of a garment; used in medieval clothing
• noun:   a slit in a garment that exposes material of a different color underneath; used in Renaissance clothing
• noun:   a sharp projection on an edge or surface

  Example: "He clutched a jag of the rock"

• verb:   cut teeth into; make a jagged cutting edge