Zymogen /(?)/

Zym·o·gen

Zymogen

n.
  1. A mother substance, or antecedent, of an enzyme or chemical ferment; -- applied to such substances as, not being themselves actual ferments, may by internal changes give rise to a ferment. (Physiol. Chem.)
    The pancreas contains but little ready-made ferment, though there is present in it a body, zymogen, which gives birth to the ferment.