A
- ABV (Alcohol by Volume)
- The percentage of alcohol in a spirit. Bourbon must be distilled to no more than 80% ABV (160 proof) and enter the barrel at no more than 62.5% ABV (125 proof). Most bourbon is bottled between 40% and 65% ABV.
- Age Statement
- The number on a bottle indicating the minimum age of the youngest whiskey in the blend. A "12 Year" bourbon may contain older whiskey, but nothing younger than 12 years. Bourbon aged less than 4 years must carry an age statement by law. Read more: bourbon age statements explained →
- Angel's Share
- The portion of whiskey lost to evaporation during barrel aging — typically 2–4% per year in Kentucky's climate. Over a decade, a barrel can lose 30–40% of its contents. The angels drink well.
- American Whiskey
- A broad category covering any whiskey distilled in the United States, including bourbon, rye, Tennessee whiskey, corn whiskey, and wheat whiskey. Each has its own legal requirements.
B
- Backset
- The thin, acidic liquid left in the still after distillation, also called "setback" or "spent beer." Added to the next mash to control pH, prevent bacterial contamination, and maintain flavor consistency. This is the "sour" in sour mash.
- Barrel Entry Proof
- The proof at which new-make spirit enters the barrel for aging. Federal law caps this at 125 proof (62.5% ABV) for bourbon. Lower entry proof (like Wild Turkey's 110) means more water in the barrel and different flavor extraction. Higher entry proof yields more barrels per distillation run but a different character. Read more: how bourbon is made →
- Barrel Proof / Barrel Strength
- Bourbon bottled at the same proof it reached in the barrel, with no water added to reduce strength. Proof varies from barrel to barrel — typically 110–140 proof. Examples include Elijah Craig Barrel Proof and Stagg Jr. Read more: barrel proof vs cask strength vs bottled-in-bond →
- Bib (Bottled-in-Bond)
- See Bottled-in-Bond.
- Bottled-in-Bond
- A designation under the Bottled-in-Bond Act of 1897 requiring: (1) product of one distillery, (2) one distilling season, (3) aged at least 4 years in a federally bonded warehouse, (4) bottled at exactly 100 proof. America's first consumer protection law for spirits. Examples: Evan Williams BiB, Old Grand-Dad BiB, Henry McKenna 10 Year BiB. Read more: barrel proof vs cask strength vs bottled-in-bond →
- Bourbon
- American whiskey made from a mash of at least 51% corn, distilled to no more than 160 proof, entered into new charred oak barrels at no more than 125 proof, and bottled at a minimum of 80 proof. No coloring or flavoring additives allowed. Contrary to popular belief, it does not have to be made in Kentucky — though about 95% of it is. Read more: how bourbon is made →
C
- Cask Strength
- Functionally the same as barrel proof — bottled without dilution. The term is more common with Scotch and international whiskey, though some American brands (Jack Daniel's Cask Strength) use it too. Read more: barrel proof vs cask strength →
- Char Level
- The degree to which the inside of an oak barrel is burned before filling. Levels range from #1 (light, 15 seconds) to #4 (heavy, 55+ seconds, called "alligator char" for its cracked, scaly appearance). Higher char levels create more caramelized sugars in the wood, adding vanilla, caramel, and smoky notes. Most bourbon uses #3 or #4 char.
- Charcoal Filtering (Lincoln County Process)
- The process of dripping new-make whiskey through sugar maple charcoal before barrel aging. Required for Tennessee whiskey (Jack Daniel's, George Dickel) and is technically what distinguishes Tennessee whiskey from bourbon.
- Column Still (Continuous Still)
- A tall, multi-plate still that runs continuously, separating alcohol from the wash as it rises through perforated plates. More efficient than pot stills. Nearly all bourbon is made on column stills, sometimes called "beer stills."
- Cooper / Cooperage
- A cooper is a craftsperson who makes or repairs wooden barrels. A cooperage is the facility where barrels are built. Major bourbon cooperages include Independent Stave Company and Brown-Forman's own cooperage in Louisville.
- Corn Whiskey
- Whiskey made from at least 80% corn. Unlike bourbon, it does not need to be aged in new charred oak — it can be unaged or aged in used or uncharred barrels. Mellow Corn is the most well-known example.
D
- Devil's Cut
- Jim Beam's trademarked term for the whiskey absorbed into the barrel wood during aging — the opposite of the angel's share. Beam extracts this liquid by tumbling emptied barrels with water.
- Distiller's Beer
- The fermented liquid (essentially a low-alcohol beer, 7–10% ABV) that goes into the still for distillation. Also called "wash" or "fermented mash."
- Doubler
- A pot-still-like vessel used for the second distillation in bourbon production. The low wines from the column still pass through the doubler to increase proof and refine flavor. Similar to a thumper but operates differently — liquid is pumped in rather than driven by steam pressure.
- DSP (Distilled Spirits Permit)
- The federal permit number assigned to each distillery by the TTB. Appears on labels and can help identify where a bourbon was actually distilled. DSP-KY-354 is MGP's Indiana facility (yes, it has a Kentucky number — long story).
E
- Extraction
- The process by which whiskey pulls flavor compounds (vanillin, tannins, lactones, caramelized sugars) from the charred oak barrel during aging. Temperature swings accelerate extraction as the liquid expands into and contracts out of the wood grain.
F
- Fermentation
- The process where yeast converts sugars in the cooked grain mash into alcohol and CO2, producing distiller's beer. Bourbon fermentation typically takes 3–5 days in large open-top or closed fermenters. Each distillery guards its yeast strain carefully.
- Fingerprint (Barrel Fingerprint)
- The unique flavor profile contributed by a specific barrel's wood grain, char level, and warehouse position. No two barrels produce identical whiskey — which is why single barrel bourbon varies from release to release.
- Finish
- Two meanings: (1) The aftertaste that lingers after swallowing — its length, character, and complexity are key to a spirit's quality. (2) A secondary maturation in a different cask type (wine barrel finish, port finish, rum finish) to add additional flavor layers.
G
- Grain-In
- The start of the distilling process when grains are milled and added to hot water in the cooker. Different grains are added at different temperatures — corn first (highest), then rye or wheat, then malted barley (lowest) to preserve its enzymes.
- Greenfield Distillery
- A newly built distillery without existing aged stock. Greenfield operations often source whiskey from other distillers (like MGP) while their own barrels mature. Most craft distilleries start this way.
H
- Heads / Hearts / Tails
- The three fractions of a distillation run. Heads (foreshots) contain harsh methanol and acetone — discarded. Hearts are the desirable middle cut — this becomes whiskey. Tails contain heavier fusel oils — sometimes recycled. Where a distiller makes the "cut" between fractions defines their spirit's character.
- High-Rye Bourbon
- Bourbon with a higher-than-typical proportion of rye in its mash bill — generally 20% or more. Produces spicier, more peppery, and more complex flavor profiles. Examples: Four Roses Single Barrel (35% rye), Old Grand-Dad (27%), Bulleit (28%). Read more: bourbon mash bills explained →
K
- Kentucky Bourbon Trail
- An organized tour route connecting major Kentucky distilleries, operated by the Kentucky Distillers' Association. The main trail includes Buffalo Trace, Maker's Mark, Wild Turkey, Woodford Reserve, Heaven Hill, Jim Beam, Four Roses, and others. The Craft Trail features smaller operations.
- Kentucky Chew
- A tasting technique popularized by the late bourbon legend Fred Noe (Jim Beam) — taking a sip of bourbon and literally chewing it, working it across every part of your mouth to engage all taste receptors before swallowing.
L
- Lincoln County Process
- See Charcoal Filtering.
- Low Wines
- The liquid that comes off the first distillation (column still) before the second distillation (doubler or thumper). Typically around 125 proof. This goes into the second still for further refinement.
M
- Malted Barley
- Barley that has been soaked, allowed to germinate, and then dried. The germination activates enzymes that convert starches into fermentable sugars during mashing. Every bourbon mash bill includes malted barley (typically 5–15%) for this enzymatic function. Read more: bourbon mash bills explained →
- Mash / Mash Bill
- The mash is the mixture of grains and water cooked together to convert starches to sugars. The mash bill is the grain recipe — the specific percentages of corn, rye (or wheat), and malted barley. A distillery's mash bill is one of its most defining characteristics. Read more: bourbon mash bills explained →
- Master Distiller
- The person responsible for overseeing all aspects of whiskey production at a distillery — from grain selection through aging and blending decisions. Notable current and recent master distillers include Chris Morris (Woodford Reserve), Brent Elliott (Four Roses), and Denny Potter (Maker's Mark).
- Mingling
- The process of combining whiskey from multiple barrels before bottling to achieve a consistent flavor profile. This is what happens with "small batch" and most standard releases. The opposite of single barrel bottling.
- MSRP (Manufacturer's Suggested Retail Price)
- The recommended retail price set by the producer. For allocated or limited-release bourbon, actual shelf prices often far exceed MSRP. Secondary market prices can be 5–20x MSRP for highly sought bottles.
- MGP (Midwest Grain Products)
- A large distillery in Lawrenceburg, Indiana that produces whiskey for dozens of brands. Many "craft" bourbons and ryes are actually sourced from MGP. Not a bad thing — MGP makes excellent whiskey. Their 95/5 rye mash bill is legendary. Brands that source from MGP include Bulleit Rye, Smooth Ambler, George Remus, and Redemption.
N
- NAS (No Age Statement)
- A bottle without an age statement on the label. If labeled "straight bourbon," the youngest whiskey is at least 4 years old. NAS doesn't mean young — Buffalo Trace, Maker's Mark, and Woodford Reserve are all NAS with estimated ages of 6–9 years. Brands drop age statements for blending flexibility. Read more: bourbon age statements explained →
- New Charred Oak
- Federal law requires bourbon to be aged in brand new, charred oak barrels (almost always American white oak). This is one of the key requirements that separates bourbon from other whiskeys. After use, these barrels are typically sold to Scotch, tequila, rum, or craft beer producers for secondary aging.
- Nose
- The aroma of a spirit, and the act of smelling it. "Nosing" bourbon in a tulip-shaped glass (like a Glencairn) concentrates the aromas and reveals layers of scent that a wider glass would dissipate. The nose often previews what you'll taste on the palate.
O
- Over-Oaked
- A tasting term for bourbon that has spent too long in the barrel, extracting excessive tannins and woody bitterness. More common in bourbons aged 15+ years in Kentucky's hot climate. Personal tolerance varies — some drinkers love heavy oak character.
P
- Palate
- The flavor experience when the spirit is on your tongue — distinct from the nose (aroma) and the finish (aftertaste). A good bourbon shows different characteristics on the palate than on the nose.
- Private Barrel / Store Pick
- A single barrel selected by a retailer, bar, or bourbon group from a distillery's warehouse. The buyer tastes multiple barrels and chooses their favorite. Store picks often offer exceptional quality and unique profiles not found in standard releases.
- Proof
- A measure of alcohol content equal to twice the ABV percentage. 100 proof = 50% ABV. 80 proof (the legal minimum for bourbon) = 40% ABV. Barrel-proof bourbon typically ranges from 110 to 140 proof.
R
- Rickhouse (Rackhouse)
- A warehouse where bourbon barrels are stored during aging. Traditional rickhouses are multi-story buildings where barrels rest on wooden ricks. Placement matters: upper floors are hotter (more extraction, faster aging), lower floors are cooler (slower, more nuanced development). Some distilleries rotate barrels between floors; most don't. Read more: how bourbon is made →
- Rye Whiskey
- Whiskey made from a mash of at least 51% rye grain (rather than corn). Follows the same production rules as bourbon otherwise. Typically spicier and drier than bourbon. Not to be confused with "high-rye bourbon," which still has a corn-majority mash bill.
S
- Single Barrel
- Bourbon drawn from one individual barrel rather than blended from multiple barrels. Every bottle from a single barrel should taste the same, but each barrel is unique — so one release can differ significantly from the next. Examples: Blanton's, Four Roses Single Barrel, Knob Creek Single Barrel.
- Small Batch
- A blend of a select number of barrels, chosen for complementary flavor profiles. There is no legal definition of "small" — it could be 10 barrels or 200. The term is more marketing than regulation. Examples: Knob Creek Small Batch, Woodford Reserve, Basil Hayden's.
- Sour Mash
- A process where a portion of spent mash (backset) from the previous distillation is added to the new mash. This controls pH, prevents bacterial growth, and adds flavor consistency between batches. Nearly all bourbon uses the sour mash process — it's the standard, not a special technique.
- Sourced Whiskey
- Whiskey purchased from another distillery and bottled under a different brand name. Common and not inherently negative — many excellent brands source from MGP, Barton, or other established producers. The issue is transparency: reputable brands disclose sourcing; questionable ones imply they distilled it themselves.
- Straight Bourbon
- Bourbon that has been aged for at least 2 years and contains no added coloring, flavoring, or other spirits. If aged less than 4 years, the age must be stated on the label. Most bourbon you see on shelves qualifies as "straight."
- Sweet Mash
- A less common process that uses fresh water and yeast (no backset from previous distillation) in each new mash. Produces a different flavor profile — often described as brighter and fruitier. Wilderness Trail and some craft distillers use sweet mash.
T
- Tails
- See Heads / Hearts / Tails.
- Tater
- Bourbon slang for a hype-driven buyer who chases allocated bottles, pays inflated secondary prices, and collects rather than drinks. Named for the idea of being a "couch potato" who sits on bottles. Used affectionately (sometimes) within the bourbon community.
- Tennessee Whiskey
- Legally, bourbon that is made in Tennessee and filtered through sugar maple charcoal before barreling (the Lincoln County Process). Jack Daniel's is the most famous example. George Dickel and Nelson's Green Brier also qualify. Yes, technically it meets the definition of bourbon — but don't say that in Lynchburg.
- Thumper
- A type of second distillation vessel that uses steam pressure from the first still to redistill the low wines. The thumping sound it makes gives it its name. Functions similarly to a doubler but uses a different mechanism. Woodford Reserve uses copper pot stills instead of a thumper or doubler.
- TTB (Alcohol and Tobacco Tax and Trade Bureau)
- The federal agency that regulates the production, labeling, and advertising of distilled spirits in the United States. The TTB defines what can legally be called bourbon, rye, straight whiskey, and so on. Their Standards of Identity are the rulebook.
W
- Wash
- See Distiller's Beer.
- Wheated Bourbon
- Bourbon that uses wheat instead of rye as the secondary grain in its mash bill. Produces a softer, sweeter, and smoother profile compared to high-rye bourbons. Famous examples: Maker's Mark, Weller, Pappy Van Winkle, and Larceny. Read more: bourbon mash bills explained →
- White Dog (White Whiskey)
- Unaged new-make spirit straight off the still — clear, raw, and high-proof. Some distilleries sell white dog as a product (Buffalo Trace White Dog, Jim Beam's Jacob's Ghost). Gives you a sense of the base spirit before oak aging transforms it.
- White Oak (Quercus alba)
- The species of oak used for virtually all bourbon barrels. American white oak is chosen for its tight grain (resists leaking), high vanillin content, and ability to impart caramel, vanilla, and spice notes during aging. Most barrel staves are air-dried for 6–9 months before coopering.
Y
- Yeast
- The microorganism that converts sugars to alcohol during fermentation. Every distillery maintains its own proprietary yeast strain — some dating back generations. Wild Turkey's yeast strain has been in use since the 1950s. Four Roses uses five different yeast strains to create their ten distinct bourbon recipes.
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