The Collaborative International Dictionary of English v.0.48:
Fibrin \Fi"brin\, n. [Cf. F. fibrine. See Fiber.] (Physiol.
1. 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. 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
3. An albuminous body, resembling animal fibrin in
composition, found in cereal grains and similar seeds;
Fibrin factors (Physiol.), the albuminous bodies,
paraglobulin and fibrinigen in the blood, which, by the
action of the fibrin ferment, are changed into fibrin, in
Fibrin ferment (Physiol. Chem.), a ferment which makes its
appearance in the blood shortly after it is shed, and is
supposed to be the active agent in causing coagulation of
the blood, with formation of fibrin.