1. (n.) A white, albuminous, fibrous substance, formed in the coagulation of the blood either by decomposition of fibrinogen, or from the union of fibrinogen and paraglobulin which exist separately in the blood. It is insoluble in water, but is readily digestible in gastric and pancreatic juice.

2. (n.) The white, albuminous mass remaining after washing lean beef or other meat with water until all coloring matter is removed; the fibrous portion of the muscle tissue; flesh fibrin.

3. (n.) An albuminous body, resembling animal fibrin in composition, found in cereal grains and similar seeds; vegetable fibrin.