Scotch whisky whisky" is any spirit that qualifies as a single malt Scotch whisky or as a blended Scotch whisky. The latter exclusion is to ensure that a blended Scotch whisky produced from single malt(s) and single grain(s) distilled at the same distillery does not also qualify as single grain Scotch whisky. Three types of blends are defined for Scotch whisky: The five Scotch whisky definitions are structured in such a way that the categories are mutually exclusive. The 2009 regulations changed the formal definition of blended Scotch whisky to achieve this result, but in a way that reflected traditional and current
American whiskey it is aged, it must be aged in used or uncharred oak barrels "at not more than 62.5% alcohol by volume (125 proof)". In practice, if corn whiskey is aged, it is usually aged in used bourbon barrels. Straight whiskey is whiskey that was distilled to not more than 80% alcohol by volume (160 proof) that has been aged for at least two years at a starting alcohol concentration of not more than 62.5%. It has not been blended with any other spirits, colorings, or additives. A straight whiskey that also meets one of the other above definitions is referred