ABV
Alcohol by volume. The percentage of a liquid that is pure alcohol. A whiskey labelled 46% ABV contains 46 millilitres of pure alcohol per 100 millilitres of liquid.
Age statement
A declared age such as “12 years old.” For whiskey containing several casks or batches, the number normally refers to the youngest spirit in the bottle under the applicable rules.
Angel’s share
The portion of spirit that evaporates through an oak cask during maturation. The rate varies with climate, warehouse conditions and time.
Barrel proof / cask strength
Whiskey bottled at, or close to, the alcoholic strength at which it leaves the cask. The phrase does not promise one universal ABV.
Blend
A combination of whiskies. The legal meaning changes by country: blended Scotch, for example, combines one or more single malt Scotch whiskies with one or more single grain Scotch whiskies.
Cask finish
A second period of maturation in a different cask after the main maturation. Producers use finishing to add or redirect aromas and flavours.
Chill filtration
A process that cools whiskey and passes it through filters to reduce compounds that can cause haze at low temperature or strength.
Mash bill
The recipe of grains used for fermentation, a term encountered most often in American whiskey.
Peat
Partially decomposed plant matter from wetlands. When burned to dry malt, its smoke can add phenolic aromas often described as earthy, medicinal or smoky.
Proof
A scale for alcoholic strength. In the United States, proof is twice the ABV: 100 proof equals 50% ABV.
Single malt
In Scotch, whisky made at one distillery from water and malted barley, using batch distillation in pot stills. “Single” means one distillery, not one cask.
Wash
The fermented, beer-like liquid that enters the first still in malt whisky production.