1. A starchy, sugary mixture of grains and water (frequently malted barley, corn, rye, and/or wheat) that is fermented in the production of beer, whiskey, vodka, and other alcoholic beverages. Different combinations of grains have a significant effect on the flavor of the alcohol that is produced (e.g., whiskeys made from a corn mash, like bourbon, tend to be sweeter than whiskeys made from a rye mash, which tend to be spicier).
  2. A step in the fermentation process wherein grains are boiled to release their sugars before adding yeast.