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.

Ferment \Fer*ment"\, v. t. [imp. & p. p. {Fermented}; p. pr. &
   vb. n. {Fermenting}.] [L. fermentare, fermentatum: cf. F.
   fermenter. See {Ferment}, n.]
   To cause ferment of fermentation in; to set in motion; to
   excite internal emotion in; to heat.

         Ye vigorous swains! while youth ferments your blood.
                                                  --Pope.

Ferment \Fer*ment"\, v. i.
   1. To undergo fermentation; to be in motion, or to be excited
      into sensible internal motion, as the constituent
      oarticles of an animal or vegetable fluid; to work; to
      effervesce.

   2. To be agitated or excited by violent emotions.

            But finding no redress, ferment an rage. --Milton.

            The intellect of the age was a fermenting intellect.
                                                  --De Quincey.

Source : WordNet®

ferment
     n 1: a state of agitation or turbulent change or development;
          "the political ferment produced a new leadership";
          "social unrest" [syn: {agitation}, {fermentation}, {unrest}]
     2: a substance capable of bringing about fermentation
     3: a process in which an agent causes an organic substance to
        break down into simpler substances; especially, the
        anaerobic breakdown of sugar into alcohol [syn: {zymosis},
         {zymolysis}, {fermentation}, {fermenting}]
     4: a chemical phenomenon in which an organic molecule splits
        into simpler substances [syn: {fermentation}]

ferment
     v 1: be in an agitated or excited state; "The Middle East is
          fermenting"; "Her mind ferments"
     2: work up into agitation or excitement; "Islam is fermenting
        Africa"
     3: cause to undergo fermentation; "We ferment the grapes for a
        very long time to achieve high alcohol content"; "The
        vintner worked the wine in big oak vats" [syn: {work}]
     4: go sour or spoil; "The milk has soured"; "The wine worked";
        "The cream has turned--we have to throw it out" [syn: {sour},
         {turn}, {work}]