Reference

The whiskey glossary

45 terms, defined plainly, each linked to the guide that explains it properly. From ABV to white dog.

ABV

Alcohol by volume, the percentage of a spirit that is ethanol. Standard unit outside the United States. American proof is exactly twice ABV.guide

Age statement

The age printed on a label. By law it reflects the youngest whiskey in the bottle, not the average or the oldest.guide

Angel's share

The portion of a barrel's contents lost to evaporation through the wood during aging. Larger in hot, dry climates.guide

Barrel proof

Whiskey bottled at the strength it left the barrel, without dilution. Also called cask strength. Not legally defined but used honestly by the trade.guide

Blended malt

Scotch made by combining single malts from more than one distillery, with no grain whisky. Formerly called vatted malt.guide

Blended Scotch

Legally, malt whisky combined with grain whisky. The style of most of the world's best-selling Scotch.guide

Bottled-in-bond

American whiskey from one distillery and one season, aged at least four years in a bonded warehouse, bottled at exactly 100 proof. A 1897 provenance guarantee.guide

Bourbon

American whiskey from at least 51 percent corn, aged in new charred oak, distilled to no more than 160 proof and barreled at no more than 125. Made anywhere in the United States.guide

Cask strength

See barrel proof. Whiskey bottled undiluted.guide

Char

The burnt inner layer of a new barrel, created by firing the inside. Filters harsh compounds and contributes color and caramelized flavor.guide

Chill filtration

Cooling whiskey before filtering to remove compounds that would cloud it at low temperature. Skipped in non-chill-filtered releases.guide

Composition

The share of a blend contributed by each component, by current volume. In an infinity bottle, it shifts with every pour.guide

Coverage

In a blended mash bill, the share of the bottle's volume for which grain data actually exists. Thief and Blend reports it rather than backfilling unknowns.guide

Dilution

Adding water to lower proof. Governed by V1 x P1 = V2 x P2; the alcohol is conserved and spread through more volume.guide

Finish

Two meanings. The flavor that lingers after swallowing, or a second cask or wood treatment applied after primary aging, as in port-finished.guide

Headroom

How much of a given whiskey can be added to a blend before the blend crosses a target proof. Solvable from the blend formula.guide

High rye

A bourbon mash bill with a rye share well above the typical 10 to 15 percent, often 20 to 35 percent. Reads as spicier.guide

Infinity bottle

An ongoing personal blend that is added to and poured from indefinitely and never emptied. A single-vessel solera.guide

Ledger

An ordered record of every event in a bottle's life: pours in, pours out, dilutions, splits, merges. Everything else is computed from it.guide

Malt

Malted barley: barley that has been germinated and dried. The base of Scotch and a minor grain in most bourbon mash bills, where it supplies enzymes.guide

Marrying

The period after blending in which combined whiskeys integrate. Fresh blends taste disjointed; married blends taste whole. Distilleries schedule weeks for it.guide

Mash bill

The grain recipe of a whiskey: percentages of corn, rye, wheat, and malted barley. Some distilleries publish it, many do not.guide

Merge

Pouring one bottle into another. In blending records, lineage should pass through untouched so nothing is counted twice.guide

Neck pour

The first pour from a freshly opened bottle, often thought to taste different from later pours as the whiskey breathes.guide

Non-chill filtered

Whiskey that skipped chill filtration, keeping compounds that add texture and may cause haze with ice or cold.guide

Oxidation

Slow chemical change in an open bottle as whiskey contacts air. Usually softens character over months. Driven by headspace.guide

Proof

American measure of alcohol strength, exactly twice ABV. 100 proof is 50 percent alcohol. Descended from a gunpowder test.guide

Proof gallon

A US tax unit: one gallon at 100 proof. The V x P arithmetic of blending is proof-gallon arithmetic in miniature.guide

Rickhouse

A whiskey aging warehouse, traditionally uninsulated and several floors tall. Position within it strongly affects how a barrel ages.guide

Rye whiskey

American whiskey from at least 51 percent rye grain, otherwise under the same rules as bourbon. Distinct from Canadian rye, which may contain little rye.guide

Sandbox

In Thief and Blend, a mode that previews the effect of hypothetical pours without recording them.guide

Ship of Theseus

The paradox of an object whose every part has been replaced. Applied to an infinity bottle, the question of how much original liquid remains, which can be computed.guide

Single barrel

Whiskey drawn from one barrel and not blended with others. Varies bottle to bottle by design.guide

Single malt

Whisky from one distillery made entirely from malted barley. May still be a blend of many casks from that distillery.guide

Small batch

A marketing term with no legal definition. A batch may be a few barrels or several hundred.guide

Solera

A fractional blending system, developed for sherry, in which a vessel is never fully emptied and is topped up with younger stock. The ancestor of the infinity bottle.guide

Sour mash

A production method that adds spent mash from a previous batch to the new one for consistency. Nearly universal in bourbon; not a quality marker.guide

Split

Dividing a bottle into two, each inheriting the same blend and lineage, free to diverge afterward.guide

Stave

One of the wooden planks of a barrel. Also a piece of oak added to whiskey for finishing.guide

Straight

American whiskey aged at least two years with no added color or flavor. Under four years, the age must be stated.guide

Tannin

Astringent compounds extracted from oak. In moderation they add structure; in excess, bitterness and dryness. Small barrels over-deliver them.guide

Thief

The tube, traditionally copper, used to draw a sample from a barrel through the bung hole. A thumb over the vent holds the sample.guide

Vatting

Combining casks of whisky into a batch. The older term for what is now called blended malt when done across distilleries.guide

Wheated bourbon

Bourbon whose secondary grain is wheat rather than rye. Reads softer and sweeter. Maker's Mark and Weller are examples.guide

White dog

Unaged whiskey straight from the still, clear and grain-forward. Also called new make.guide