Source : Webster's Revised Unabridged Dictionary (1913)

Ferment \Fer"ment\, n. [L. fermentum ferment (in senses 1 & 2),
   perh. for fervimentum, fr. fervere to be boiling hot, boil,
   ferment: cf. F. ferment. Cf. 1st {Barm}, {Fervent}.]
   1. That which causes fermentation, as yeast, barm, or
      fermenting beer.

   Note: Ferments are of two kinds: ({a}) Formed or organized
         ferments. ({b}) Unorganized or structureless ferments.
         The latter are also called {soluble or chemical
         ferments}, and {enzymes}. Ferments of the first class
         are as a rule simple microscopic vegetable organisms,
         and the fermentations which they engender are due to
         their growth and development; as, the {acetic ferment},
         the {butyric ferment}, etc. See {Fermentation}.
         Ferments of the second class, on the other hand, are
         chemical substances, as a rule soluble in glycerin and
         precipitated by alcohol. In action they are catalytic
         and, mainly, hydrolytic. Good examples are pepsin of
         the dastric juice, ptyalin of the salvia, and disease
         of malt.