/ Dictionary / Index F fibrin: Meaning and Definition of Find definitions for: fi•brin Pronunciation: (fī'brin), [key] — n. the insoluble protein end product of blood coagulation, formed from fibrinogen by the action of thrombin in the presence of calcium ions. a fibrinlike substance found in some plants; gluten. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: fibrin (Thesaurus) fibrilliform fibrino- Related Content Daily Word Quiz: cetacean Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language