Straight whiskey (or straight whisky), as defined in United States law, is whiskey that is distilled from a fermented (malted or unmalted) cereal grain mash to a concentration not exceeding 80% alcohol by volume (abv) and aged in new charred oak barrels for at least two years at a concentration not exceeding 62.5% at the start of the aging process.[1] Domestic sales of straight whiskey surpassed 27 million 9-liter cases in 2021.[2]
The only allowed modifications to straight whiskey prior to its bottling consist of batching whiskey from different barrels (and sometimes from different distilleries, although only from within the same state), chill filtering the whiskey, and adding water to reduce proof while retaining at least a 40% abv concentration. This definition is established for production of American whiskey for consumption within the United States as per the U.S federal Standards of Identity for Distilled Spirits.[1] The regulations do not necessarily apply to American whiskey made for export.[3]
Alternatively, straight can be regarded as a synonym for ordering or serving whiskey neat, sans any water, ice, mixers, or other liquors.
TTB was invoked but never defined (see the help page).