For something to ferment, its chemical structure changes, and the resulting change sometimes contains alcohol. The process can also be called fermentation.
Something can be described as fermentable.
To cause something to foment is to agitate it or increase its growth. There is a pejorative connotation with this word and its synonyms include incite.
Someone who foments something or someone is called a fomenter.
In some instances ferment can be a synonym for foment, but foment does not carry all of the definitions of ferment.
When sugars in foods turn into acids, gases, or alcohol (due to a lack of oxygen) the foods ferment. [Medical Daily]
Hopelessness ferments when you feel powerless. [PBS]
Beset by a seasonal rash of birds inebriated on fermented berries, Yukon wildlife officials have readied a series of miniature drunk tanks to help the erratic avians sober up. [National Post]
But fermentation, an ancient method of food preservation, is making a big comeback. [Farm and Dairy]
In the case of Russia, still fomenting war in Eastern Ukraine, isolating sanctions are the only realistic way that Europe can respond in an effort to save lives. [The Daily Beast]
They see Al Jazeera, based in Qatar, as a supporter of the Brotherhood and a fomenter of unrest. [The Australian]
Managers, too, stand accused of failing to root for NHS Grampian; of being remote; of making heartfelt concern sound like fomentation, and dismissing constructive criticism as rogue voices. [Evening Express]