pepsinogen

from WordNet (r) 3.0 (2006)

pepsinogen
    n 1: precursor of pepsin; stored in the stomach walls and
         converted to pepsin by hydrochloric acid in the stomach

from The Collaborative International Dictionary of English v.0.48

Pepsinogen \Pep*sin"o*gen\, n. [Pepsin + -gen.] (Physiol. Chem.)
   A proenzyme, the antecedent of the enzyme pepsin. A substance
   contained in the form of granules in the peptic cells of the
   gastric glands. It is readily convertible into pepsin. Also
   called {propepsin}.
   [1913 Webster]