The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   Note: Ferments are of two kinds: (a) Formed or organized
         ferments. (b) Unorganized or structureless ferments.
         The latter are now called enzymes and were formerly
         called soluble ferments or chemical ferments.
         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 they are proteins 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. Before 1960 the term "ferment" to
         mean "enzyme" fell out of use. Enzymes are now known to
         be globular proteins, capable of catalyzing a wide
         variety of chemical reactions, not merely hydrolytic.
         The full set of enzymes causing production of ethyl
         alcohol from sugar has been identified and individually
         purified and studied. See enzyme.
         [1913 Webster +PJC]

   2. Intestine motion; heat; tumult; agitation.
      [1913 Webster]

            Subdue and cool the ferment of desire. --Rogers.
      [1913 Webster]

            the nation is in a ferment.           --Walpole.
      [1913 Webster]

   3. A gentle internal motion of the constituent parts of a
      fluid; fermentation. [R.]
      [1913 Webster]

            Down to the lowest lees the ferment ran. --Thomson.
      [1913 Webster]

   ferment oils, volatile oils produced by the fermentation of
      plants, and not originally contained in them. These were
      the quintessences of the alchemists. --Ure.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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 or fermentation in; to set in motion; to
   excite internal emotion in; to heat.
   [1913 Webster]

         Ye vigorous swains! while youth ferments your blood.
                                                  --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ferment \Fer*ment"\, v. i.
   1. To undergo fermentation; to be in motion, or to be excited
      into sensible internal motion, as the constituent
      particles of an animal or vegetable fluid; to work; to
      effervesce.
      [1913 Webster]

   2. To be agitated or excited by violent emotions.
      [1913 Webster]

            But finding no redress, ferment and rage. --Milton.
      [1913 Webster]

            The intellect of the age was a fermenting intellect.
                                                  --De Quincey.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ferment
    n 1: a state of agitation or turbulent change or development;
         "the political ferment produced new leadership"; "social
         unrest" [syn: agitation, ferment, fermentation,
         tempestuousness, 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, 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: ferment, 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, ferment, work]

Moby Thesaurus II by Grady Ward, 1.0:

281 Moby Thesaurus words for "ferment":
   acetification, acetify, acidification, acidify, acidulate,
   acidulation, ado, agent, agitate, agitation, ailment, alkalify,
   alkalization, alkalize, alterant, alterative, alterer, arouse,
   bacteria, beat, beat up, blow the coals, blubber, bluster, bobbery,
   boil, boil over, boiling, borate, bother, botheration, brawl, brew,
   broil, brouhaha, bubble, bubble over, bubble up, bubbliness,
   bubbling, burble, burst, bustle, buttermilk, cacophony,
   carbon dioxide, carbonate, carbonation, catalysis, catalyst,
   catalytic agent, catalyze, chaos, chemical, chemicalization,
   chlorinate, churn, churn up, clamor, commotion, conturbation,
   convulse, convulsion, disarrange, discompose, discomposure,
   disorder, disquiet, disquietude, disturb, disturbance, dudgeon,
   ebullience, ebulliency, ebullition, eddy, effervesce,
   effervescence, effervescency, electrolysis, electrolyze,
   embroilment, enzyme, excite, excitement, fan, fan the flame,
   fanaticism, feed the fire, feery-fary, fermentation, fever,
   feverishness, fidgetiness, fidgets, fire, fit, fizz, fizzle, flap,
   flurry, fluster, flutter, flutteration, flutteriness, foam,
   foaming, foment, fomentation, foofaraw, frenzy, fret, froth,
   frothiness, frothing, fume, furor, furore, fury, fuss, fussiness,
   guggle, gurgle, heat, heat up, high dudgeon, hiss, homopolymerize,
   hubbub, huff, hullabaloo, hurly-burly, hurry, hurry-scurry,
   hydrate, hydrogenate, hydrogenation, hydroxylate, impassion,
   incense, incite, inflame, innovationist, innovator, inquietude,
   instigate, introducer, isomerism, isomerize, jitters, jumpiness,
   leaven, leavening, maelstrom, malaise, metamerism, metamerization,
   miff, modificator, modifier, moil, mother, nerviness, nervosity,
   nervousness, nettle, nitrate, nitration, outcry, oxidation,
   oxidization, oxidize, paddle, pandemonium, passion, pell-mell,
   pepsin, pepsinate, peroxidize, perturb, perturbate, perturbation,
   pet, phosphatization, phosphatize, pique, plop, polymerism,
   polymerization, polymerize, position isomerism, pother, precursor,
   provoke, put up to, racket, rage, raise, rally, reduce, reduction,
   restiveness, restlessness, rile, ripple, rise, roil, roughen,
   rouse, rout, row, ruckus, ruffle, rumple, rumpus, saturization,
   scramble, seethe, seething, set on, shake, shake up, sic on,
   simmer, smolder, soda, sour, sparkle, spasm, spumescence, spurt,
   stew, stir, stir the embers, stir up, storminess, sulfate,
   sulfatize, sulfonate, sweat, swirl, swirling, tempestuousness,
   tickle, tiff, to-do, transformer, transmogrifier, trepidation,
   trepidity, trouble, tumult, tumultuation, tumultuousness,
   turbidity, turbulence, turmoil, turn sour, twitter, unease,
   unquiet, unrest, upheaval, uproar, upset, upturn, vinegar, vortex,
   whet, whip, whip up, whirl, whisk, wildness, work, work up,
   working, yeast, yeastiness, zeal, zealousness