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
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.
Subdue and cool the ferment of desire. --Rogers.
the nation is in a ferment. --Walpole.
3. A gentle internal motion of the constituent parts of a
fluid; fermentation. [R.]
Down to the lowest lees the ferment ran. --Thomson.
ferment oils, volatile oils produced by the fermentation of
plants, and not originally contained in them. These were
the quintessences of the alchemists. --Ure.