Definition of "fibrin" [fi•brin]

• An elastic, insoluble, whitish protein produced by the action of thrombin on fibrinogen and forming an interlacing fibrous network in the coagulation of blood. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "It probably does not exist as such, but there are present in the blood certain substances known as _paraglobulin_ and _fibrinogen_, which by the action of a third substance, _fibrin ferment_ under certain circumstances, form fibrin and so cause coagulation."
• "During the coagulation a fine-meshed network of fibrin is precipitated."
• "Blood clots form when platelets, usually smooth, produce tiny threads called fibrin, which is due to inflammation, according to the University of Pennsylvania School of Medicine."