1. A normal ongoing process that dissolves fibrin and results in the removal of small blood clots.
2. The dissolution of fibrin by enzymatic action.
3. A complicated system of biochemical reactions for lysis (dissolution or destruction of cells such as blood cells) of clots in the vascular system.

The insoluble protein fibrin is broken down by the enzyme plasmin which is activated at the same time as the coagulation process of blood.

There is normally a balance between coagulation and fibrinolysis; an abnormal increase in the latter causes excessive bleeding.