Fibrinous refers to a type of tissue or fluid that contains fibrin, a protein involved in blood clotting. When the body experiences injury or inflammation, fibrin is produced to help form a clot and prevent excessive bleeding. This process is essential for healing, as it provides a scaffold for new tissue to grow. In medical contexts, fibrinous material can be found in various conditions, such as fibrinous pleuritis, where fibrin accumulates in the pleural cavity of the lungs. It can also appear in fibrinous pericarditis, affecting the heart's outer layer. The presence of fibrinous tissue often indicates an ongoing inflammatory response.