📚Reference
Glossary of IPA Terms
A working vocabulary for reading, brewing, and discussing IPAs. Terms are listed alphabetically. Where a concept has its own dedicated note, the entry links to it.
Note
This glossary covers brewing science, sensory language, and trade terms. For a chronology of the style see Timeline of IPA History; for the full note map see the Master Index.
#A–C
| Term | Definition |
|---|---|
| ABV | Alcohol By Volume — the percentage of a beer's volume that is ethanol. Most IPAs fall between 5.5% and 7.5%; see Reading an IPA Label. |
| Adjunct | A fermentable ingredient other than malted barley — oats, wheat, sugar, lactose. See Specialty Malts and Adjuncts. |
| Alpha acid | The resin compounds in hops that, once isomerized, provide bitterness. Measured as a percentage of hop weight. See Alpha Acids and Bitterness. |
| Aroma hops | Hops added late in the process to contribute scent rather than bitterness. See Bittering, Flavor, and Aroma Hops. |
| Attenuation | The degree to which yeast converts sugar into alcohol and CO2. High attenuation yields the dry finish typical of a West Coast IPA. See Fermentation. |
| Base malt | The bulk pale malt that supplies most of a beer's fermentable sugar. See Base Malts. |
| Beta acid | A hop resin that contributes little bitterness when fresh but oxidizes over time, affecting aged-hop character. See Hop Chemistry. |
| Bittering hops | Hops added early in The Boil for maximum isomerization and bitterness. See Hop Additions and Timing. |
| Biotransformation | The conversion of hop compounds by active yeast during fermentation, generating new aromatic thiols and esters. See Biotransformation. |
| BJCP | Beer Judge Certification Program — the body whose style guidelines define competition categories. See BJCP and Style Guidelines. |
| Brett | Brettanomyces, a wild yeast used in Brett IPA for funky, fruity complexity. |
| Brix | A measure of dissolved sugar, often used alongside gravity readings. See Recipe Formulation. |
| Carbonation | Dissolved CO2 that produces a beer's effervescence and contributes to perceived crispness. See Carbonation and Packaging. |
| Chloride | A water ion that accentuates malt fullness and a rounded mouthfeel. See Water Chemistry and the Sulfate-Chloride Ratio. |
| Cohumulone | A fraction of alpha acid sometimes associated with a harsher bitterness quality. See Hop Chemistry. |
| Colloidal stability | A beer's resistance to forming haze or sediment over time. See Hop Haze and Colloidal Stability. |
| Cryo hops | Concentrated lupulin powder produced by cryogenic processing, prized for intense aroma with less vegetal matter. See Cryo Hops and Lupulin Powder. |
#D–H
| Term | Definition |
|---|---|
| Diacetyl | A buttery off-flavor caused by incomplete fermentation. See Off-Flavors in IPA. |
| Double dry hop (DDH) | Adding dry hops in two separate charges to layer aroma intensity. See Double Dry Hopping. |
| Dry hopping | Adding hops after the boil — during or after fermentation — for aroma without added bitterness. See Dry Hopping. |
| EBC / SRM | Color scales for beer; SRM is the common American measure. See Reading an IPA Label. |
| Ester | A fruity aromatic compound produced by yeast, prominent in New England IPA and Belgian IPA. See Hop Aroma Compounds. |
| Final gravity (FG) | The density of beer after fermentation; the gap from original gravity indicates alcohol produced. See Recipe Formulation. |
| Flameout | The moment the boil is stopped; hops added here begin the Whirlpool and Hop Stand phase. |
| Hop burst | A late-hopping technique loading flavor and aroma additions to maximize hop character; also slang for vivid hop intensity. See Thiols and Hop Burst. |
| Hop creep | Refermentation caused by enzymes in dry hops freeing extra fermentable sugar, raising ABV and risking gushing. See Hop Creep and Refermentation and Dry Hop Creep Explained. |
| Hop fade | The loss of hop aroma as a beer ages and oxidizes. See Hop Fade and Oxidation. |
| Hop stand | A post-boil hold at sub-boiling temperature to extract aroma with minimal bitterness. See Whirlpool and Hop Stand. |
| Humulene | A hop terpene contributing herbal, woody, "noble" character. See Hop Oils and Terpenes. |
#I–M
| Term | Definition |
|---|---|
| IBU | International Bitterness Unit — the analytical measure of isomerized alpha acid in beer. Perceived bitterness can differ from the number. See IBU and Perceived Bitterness. |
| Isomerization | The heat-driven chemical change that turns insoluble alpha acids into bitter iso-alpha acids during the boil. See Isomerization of Alpha Acids. |
| Lactose | An unfermentable milk sugar added for sweetness and body, notably in Milkshake IPA. |
| Lautering | Separating sweet wort from spent grain after the mash. See Lautering and Sparging. |
| Light-struck | "Skunked" — a defect from light reacting with hop compounds. See Light-Struck Beer and Skunking. |
| Lupulin | The yellow resinous glands of the hop cone where alpha acids and oils are stored. See Cryo Hops and Lupulin Powder. |
| Mash | The hot steep of milled grain and water that converts starch to sugar. See Mashing. |
| Mouthfeel | The tactile sensation of beer — body, carbonation, astringency, creaminess. See The Science of Mouthfeel. |
| Myrcene | The dominant hop terpene, responsible for resinous, citrusy, "dank" aromas. See Hop Oils and Terpenes. |
#N–S
| Term | Definition |
|---|---|
| NEIPA | New England IPA — a soft, hazy, low-bitterness, aroma-forward style. See New England IPA. |
| Noble hops | Traditional low-alpha European aroma hops. See Noble and English Hops. |
| Original gravity (OG) | The density of wort before fermentation, indicating potential alcohol. See Recipe Formulation. |
| Oxidation | Reaction with oxygen that dulls hop aroma and creates stale, papery flavors. See Hop Fade and Oxidation. |
| Pellets | Compressed, milled hops — the most common commercial hop format. See Hop Products and Formats. |
| Polyphenol | Plant compounds from hops and malt that contribute to haze, astringency, and stability. See Hop Haze and Colloidal Stability. |
| Sparging | Rinsing the grain bed with hot water to recover residual sugar. See Lautering and Sparging. |
| Sulfate | A water ion that sharpens and accentuates hop bitterness — the classic Burton signature. See Water Chemistry and the Sulfate-Chloride Ratio. |
#T–Z
| Term | Definition |
|---|---|
| Terpene | A class of volatile hop oils (myrcene, humulene, pinene, linalool) responsible for aroma. See Hop Oils and Terpenes. |
| Terroir | The influence of growing region, soil, and climate on a hop's character. See Hop Terroir. |
| Thiol | Sulfur-containing aroma compounds delivering intense tropical, passionfruit, and grapefruit notes, often released via biotransformation. See Thiols and Hop Burst. |
| Three-tier system | The U.S. legal structure separating brewers, distributors, and retailers. See Beer Distribution and the Three-Tier System. |
| Whirlpool | The post-boil swirl that collects trub and serves as a hop-stand aroma addition. See Whirlpool and Hop Stand. |
| Wort | Unfermented sweet liquid extracted from the mash, destined to become beer. See The IPA Brewing Process Overview. |
| Yeast | The microorganism that ferments wort into beer; strain choice shapes ester and biotransformation character. See Yeast and IPA Yeast Strains. |
#Continue Reading
- Master Index — every note in the vault
- Frequently Asked Questions — common questions answered
- Hop Chemistry — the science behind the vocabulary
- BJCP and Style Guidelines — the formal style framework
- Beer Flavor Wheel — the language of tasting