Etymology: (1350–1400; ME < L fermentum yeast, fermentāre to cause to rise; akin to barm , L fervēre to boil)
Definition of 'ferment'
Princeton's WordNet
1. (noun)agitation, ferment, fermentation, tempestuousness, unrest a state of agitation or turbulent change or development "the political ferment produced new leadership"; "social unrest"
6. (verb)ferment, work 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"
7. (verb)sour, turn, ferment, work go sour or spoil "The milk has soured"; "The wine worked"; "The cream has turned--we have to throw it out"
Definition of 'ferment'
Webster Dictionary
1. (noun)ferment that which causes fermentation, as yeast, barm, or fermentingbeer
5. (verb)ferment 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
6. (verb)ferment to be agitated or excited by violent emotions
Sense: to (make something) go through a particular chemical change (as when yeast is added to dough in the making of bread) Grape juice must be fermented before it becomes wine.