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.

Source: Webster's Revised Unabridged Dictionary (1913)
 

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.

Source: Webster's Revised Unabridged Dictionary (1913)
 

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: Webster's Revised Unabridged Dictionary (1913)