For Scotch whisky, the definition is precise: single malt is made at one distillery from water and malted barley, without other cereals, and distilled in batches in copper pot stills. It must also meet the wider rules for Scotch, including maturation in Scotland for at least three years and bottling at no less than 40% alcohol by volume.
One distillery, many casks
A standard single malt bottling commonly combines many casks of different sizes, fill dates and previous uses. They all contain malt whisky from the named distillery, but a blender may assemble them to create a consistent profile. A “single cask” statement is separate and far narrower.
Not automatically smoky
Single malt is a production category, not a flavour category. Peat smoke enters the process only when peat is used while drying malt. Unpeated single malts can be grassy, fruity, waxy, nutty or spicy; peated examples range from a faint hearth note to intense smoke.
Not automatically older or better
The definition does not guarantee an age beyond the category minimum, nor does it rank quality. Grain selection, fermentation, distillation, cask management and blending skill matter more than the prestige attached to two familiar words.
Beyond Scotland
Other countries produce single malt, sometimes under different technical standards. The broad idea remains recognizable, but local law controls the exact meaning. When comparing bottles from different countries, do not assume the complete Scotch definition travels with the term.
Primary reference: Scotch Whisky Association.