If food or drink ferments or if you ferment it, it goes through a chemical change because of the action of yeast or bacteria, which may cause it to produce bubbles or heat, or turn sugars in it into alcohol.

You make wine by leaving grape juice to ferment until all the sugar has turned to alcohol. 酿葡萄酒是让葡萄汁发酵，直到所有的糖分都转化为酒精。

Sauerkraut and kimchi are both essentially fermented cabbage.

a state of confusion, change, and lack of order or fighting

The resignation of the president has left the country in ferment. 总统辞职导致国家处于动乱之中。