Generally, whiskey is defined as: An alcoholic distillate from a fermented mash of grain (e.g., barley, corn, rye, or wheat). Distilled to less than 190° proof (or 95% alcohol by volume). Possessing the taste, aroma, and characteristics generally attributed to whiskey. Stored in oak barrels (except for corn whisky). Bottled at not less than 40 percent alcohol by volume (80° proof).