fibrinogen

from WordNet (r) 3.0 (2006)

fibrinogen
    n 1: a protein present in blood plasma; converts to fibrin when
         blood clots [syn: {fibrinogen}, {factor I}]

from The Collaborative International Dictionary of English v.0.48

Fibrinogen \Fi*brin"o*gen\, n. [Fibrin + -gen.] (Physiol. Chem.)
   An albuminous substance existing in the blood, and in other
   animal fluids, which either alone or with fibrinoplastin or
   paraglobulin forms fibrin, and thus causes coagulation.
   [1913 Webster]