Wiktionary
n. Whisky made only from the malted barley of a single distillery, unblended with other whiskies.
Wikipedia
Single malt whisky is malt whisky from a single distillery, that is, whisky distilled from fermented mash made exclusively with malted grain (usually barley), as distinguished from unmalted grain.
Single malts are typically associated with single malt Scotch, though they are also produced in various other countries. Under Scotch Whisky Regulations, a "Single Malt Scotch Whisky" must be made exclusively from malted barley (although the addition of E150A caramel colouring is allowed), must be distilled using pot stills at a single distillery, and must be aged for at least three years in oak casks of a capacity not exceeding . While the Scotch model is usually copied internationally, these constraints may not apply to whisky marketed as single malt that is produced elsewhere. For example, there is no definition of the term single with relation to whisky in the law of the United States, and some American whiskey advertised as single malt whisky is produced from malted rye rather than malted barley.
Usage examples of "single malt whisky".
With the cooperation of an uncle on the general staff who arranged priority transport, Andrew kept the squadron supplied with the finest fare that his family estates in the highlands could provide, Scotch beef, grouse and salmon and venison in season, eggs and cheeses and jams, preserved fruits, and a rare and won erful single malt whisky with an unpronounceable name that came from the family-owned distillery.
Dirk Courtney splashed single malt whisky into the glasses that were set out on a silver tray on the corner of the big mahogany desk, and made a silent offer to Ronald Pye, who shook his head primly.
He threw off his coat and hat, crossed the antique Aubusson rug to the sideboard to pour himself a stiff single malt whisky.
British cabinet members confer with them in darkened Jacobean rooms redolent of single malt whisky, Cuban cigars, and treason.