Question

what is meant by fermentation.

Answer 1

there are two major definitions.
The chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence.
The process of this kind involved in the making of beer, wine, and liquor, in which sugars are converted to ethyl alcohol.

Answer 2

normally it means rotting fruit to make alcohol

Answer 3

what is meant by effervescence.