1. To produce or to undergo a gradual chemical change in which yeast, bacteria, and enzymes change sugars into alcohol or lactic acid, a colorless, odorless acid that is formed in sour milk, etc: When Mike was visiting the winery, he learned that when grape juice ferments, it is part of the production of wine.
2. To seethe or to be disturbed by social agitation or excitement in order to promote changes: Demonstrations by union workers fermented when the company decided to reduce the number of employees, including Sharon's husband.

When a certain politician was caught taking part in drugs, the legislative members were fermenting to get him to quit and when that didn't work, they voted to reduce his power of office.

3. Etymology: from Latin, "leaven or yeast"; generally an agent that causes fermenting.

1. A reference to a liquor that has been through the process of chemical changes: Beer, sherry, and other alcoholic drinks are the results of fermented processes of chemical transformations of sugar.

Most fermented drinks are developed by a process that is used to produce ethanol, the strong chemical in alcoholic drinks which come from fruits or grain.

2. Relating to leavened bread: Substances; such as, baking soda or cream of tartar, are added to batters and doughs to produce fermented bread that expands so it is light or lighter.