Glossary

Plain-English definitions of 140 common meadmaking and fermentation terms.

A B C D E F G H I K L M O P R S T W X Y

A

ABV: Alcohol by volume. The percentage of ethanol in the finished mead, expressed as a fraction of total liquid volume. Calculated from the difference between original gravity and final gravity.
Acerglyn: A mead made by replacing some or all of the honey with maple syrup, contributing the syrup’s caramel and woody character alongside the fermentable sugar.
Acetobacter: A genus of acid-producing bacteria that can spoil mead into vinegar if the must or finished mead is exposed to air for an extended period. Punch-downs and topped-up vessels reduce the exposed surface area available for it to grow.
Adjunct: Any non-honey ingredient, such as a spice, herb, fruit, hop, or oak addition, added to a mead for flavour, body, or character beyond the honey itself.
Aerating: Introducing oxygen into the must during early fermentation to support yeast growth and cell membrane health. Aeration is beneficial in the first 24–48 hours but harmful after the 1/3 sugar break when it can promote oxidation.
Airlock: A one-way valve fitted to a fermenter that lets carbon dioxide escape during fermentation while keeping outside air and contaminants out.
Airstone: A porous stone connected to an aquarium-style air pump, used to bubble oxygen through the must during aeration.
Anthocyanins: Pigment compounds extracted from grape or fruit skins during skin contact, responsible for much of the red and purple colour in pyments and melomels.
Attenuation: The degree to which yeast has fermented the available sugars in the must, expressed as a percentage of the original gravity points consumed. Higher attenuation = drier mead.
Auto-siphon: A spring-loaded siphon that primes itself with a single pump of the handle, avoiding the need to start a siphon by mouth.
Autolysis: Yeasty, meaty off-flavours that develop when a mead is left too long in contact with a thick layer of dead yeast cells after fermentation ends.

B

Back-sweetening: Adding sugar, honey, or juice to a stabilised mead after fermentation to restore sweetness without triggering renewed fermentation.
Balché (pitarrilla): A ceremonial drink from Maya tradition, made by fermenting honey and water with bark from the balché tree, historically used in ritual and community contexts.
Bentonite: A calcium montmorillonite clay used as a fining agent to clarify mead. It carries a negative charge that attracts positively charged protein particles (common in heather honey meads), causing them to clump and settle. Added at pitch or shortly after.
Black mead: A modern home-meadmaking term for mead infused with black tea, which contributes tannin and colour in place of the grape-derived tannin found in some traditional recipes.
Bochet: A style of mead made with caramelised (burned) honey. The caramelisation process changes the flavour profile significantly — adding notes of toffee, marshmallow, and dark fruit — and partially breaks down fermentable sugars, lowering predicted OG.
Bochetomel: A mead combining the bochet technique of caramelising honey before fermentation with the addition of fruit, blending the toffee and dark fruit notes of bochet with melomel character.
Bottling wand: A valved tube attached to bottling tubing that fills bottles from the bottom up and stops the flow of liquid when lifted, reducing splashing and oxygen pickup.
Braggot: A hybrid beverage made with both honey and malt (and optionally hops). It bridges the gap between mead and beer in character, and typically uses a beer or ale yeast strain.
Brix: A unit of sugar concentration equal to grams of sucrose per 100 grams of solution. In mead, Brix is used interchangeably with approximate sugar percentage and is calculated from specific gravity. The calculator uses Brix = (OG − 1.000) × 220.
Bulk aging: Conditioning a mead in a single large vessel before bottling, as opposed to aging it in individual sealed bottles.

C

Campden: Potassium or sodium metabisulphite, used to sterilise equipment and inhibit wild yeast and bacteria before pitching a cultured strain. Also used post-fermentation as an antioxidant. One Campden tablet per 4.5L is the standard dose. See Potassium metabisulphite.
Capsicumel: A mead flavoured with chilli peppers, typically added during secondary fermentation so the heat and pepper character can be adjusted to taste before bottling.
Carboy: A narrow-necked glass or plastic vessel used for fermentation or aging, the term commonly used in North America. See Demijohn.
Chitosan: A shellfish-derived fining agent, usually paired with kieselsol, that carries a positive charge to attract and clear suspended particles. Not vegan.
Chouchen: A traditional mead from Brittany, in northwestern France, historically associated with Breton culture and still produced regionally today.
CO2 volumes: The standard unit for how much carbon dioxide is dissolved in a carbonated mead, used to target a specific level of fizz.
Cold crashing: Chilling a mead close to freezing to encourage suspended yeast and haze particles to clump together and settle out.
Colloidal haze: A persistent haze caused by a stable mix of very fine particles that resist settling on their own, sometimes seen in aged or heavily blended meads.
Conical fermenter: A cone-bottomed fermentation vessel with a valve at the base, allowing sediment to be drained without racking the whole batch.
Crushed must: A pyment-making choice in which grapes are crushed with their skins and pulp left in contact with the must, extracting more tannin and colour than juice alone. See Pressed only.
Crystal malt (caramel malt): A malt that adds unfermentable body, sweetness, and colour to a braggot, rather than fermentable sugar.
Cyser: A melomel made with apples or apple juice. Cysers bridge mead and cider and are often produced with cider-focused yeast strains (e.g. WLP775) that preserve apple character while fermenting dry.
Czwórniak: A graded style of Polish mead made at roughly a 1:3 ratio of honey to water, the lowest-gravity of the four traditional Polish mead grades. Recognised as a Traditional Speciality Guaranteed (TSG) product under EU law. See Półtorak, Dwójniak, and Trójniak.

D

Dandaghare: A mead from Nepal made with the addition of Himalayan herbs and spices, reflecting the regional ingredients available at altitude.
DAP: Diammonium phosphate. An inorganic nitrogen source with a YAN density of 210 ppm/g/L. Highly concentrated and effective in early fermentation, but should not be used after the must has exceeded approximately 9% ABV, as yeast cannot assimilate inorganic ammonium at higher alcohol levels.
Degassing: Removing dissolved CO₂ from the must by stirring or agitation. Essential before each nutrient addition to prevent violent foam-over. Also done periodically during fermentation to reduce off-gas stress on yeast.
Demijohn: A narrow-necked glass or plastic vessel used for fermentation or aging, the term commonly used in the UK and elsewhere. See Carboy.
Dextrose (corn sugar): A simple sugar commonly used for priming bottle-conditioned mead, valued for fermenting cleanly and predictably.
DME (Dry Malt Extract): A powdered, pre-converted malt sugar used in braggot mode as a fermentable alternative to mashing grain. See LME.
Dwójniak: A graded style of Polish mead made at roughly a 1:1 ratio of honey to water. Recognised as a Traditional Speciality Guaranteed (TSG) product under EU law. See Półtorak, Trójniak, and Czwórniak.

E

Erythritol: A non-fermentable sugar alcohol used to back-sweeten a mead with no risk of triggering renewed fermentation.
Esters: Fruity or floral aroma compounds produced by yeast during fermentation. Different yeast strains and fermentation temperatures produce different ester profiles.

F

F:G ratio: Fructose-to-glucose ratio. Honey sugar composition varies by variety — acacia has a very high F:G (~1.60) while rapeseed has a low F:G (~0.93). Standard yeast strains preferentially ferment glucose; musts with very high F:G ratios are prone to stalling without a fructophilic yeast strain.
FAN (Free Amino Nitrogen): Amino-acid-based nitrogen naturally present in malt wort or grape juice, contributing to a must’s total assimilable nitrogen alongside other nitrogen sources.
Fermaid K: A blended nutrient containing DAP, inactivated yeast, yeast hulls, and micronutrients. YAN density: 100 ppm/g/L. More concentrated than Fermaid O; subject to the 9% ABV inorganic nitrogen cutoff.
Fermaid O: An organic nitrogen source derived from inactivated yeast cell walls. YAN density: 40 ppm/g/L. The recommended primary nutrient in TOSCA 2.0 — it provides FAN, vitamins, and cell wall components and can be used through all stages of fermentation.
Fermentation: The metabolic process by which yeast converts fermentable sugars into ethanol, carbon dioxide, and flavour compounds. In mead, primary fermentation typically runs 2–6 weeks depending on OG, temperature, yeast strain, and nutrient levels.
FG (Final Gravity): The specific gravity of the mead once fermentation has reached completion or been stopped. Used together with original gravity to calculate ABV. A fully dry mead typically finishes around 0.990–1.000.
Finings: Clarifying agents added to mead post-fermentation to accelerate clearing. Common options include bentonite (protein fining), Isinglass (collagen-based), kieselsol, and chitosan. Most home meadmakers achieve clarity with time and cold-crashing alone.
Flaming (addition timing): A spice-addition technique in which an ingredient, typically a cinnamon stick, is briefly ignited before being added to the must.
Flocculation: A yeast strain’s tendency to clump together and settle out of suspension once fermentation slows, directly affecting how quickly and clearly a mead clarifies on its own.
Free SO2: The portion of added sulfite that remains chemically active and available to inhibit microbial activity, as opposed to sulfite that has bound to other compounds in the mead.
Fructophilic: Describes a yeast strain with enhanced fructose transport capacity (typically the HXT3 gene). Fructophilic strains can metabolise fructose at the same rate as glucose, eliminating the stall risk associated with high-F:G honey varieties like acacia and tupelo.
Fructose risk tiers: A classification of how fructose-heavy a honey or honey blend is, since fructose ferments more slowly than glucose for most yeast strains and high-fructose musts are more prone to stalling.
Fusel alcohols: Harsh, hot-tasting higher alcohols produced when yeast ferments outside its ideal temperature range, particularly when fermentation runs too warm.

G

Geranium off-flavour: A distinctive off-flavour produced when malolactic bacteria convert potassium sorbate into sorbic acid, typically from adding sorbate without also using sulfite.
GoFerm PE: GoFerm Protect Evolution. A yeast rehydration nutrient that protects cell membranes during the osmotic shock of rehydrating dry yeast. Added to the warm rehydration water before the yeast, never directly to the must. YAN density: 30 ppm/g/L (for calculator purposes). Typical dose: 1.25× dry yeast weight.
Grain bill: The combination and proportion of malts used in a braggot’s recipe.
Gravity: Shorthand for specific gravity — the density of the must or mead relative to water. Gravity indicates sugar concentration before fermentation and alcohol content after. See Original Gravity, Final Gravity, and Specific Gravity.

H

Hippocras: A spiced pyment, combining grape must or juice with honey and warming spices such as cinnamon and ginger. See Pyment.
Honey must: The mixture of honey and water (and any fruit or adjuncts) before or during fermentation. "Must" is the technical term for pre-fermented fruit or honey liquid, borrowed from winemaking.
Hydrogen sulphide (H2S): A rotten-egg-smelling off-gas produced by stressed yeast, usually caused by insufficient nitrogen or oxygen during fermentation.
Hydromel: A low-gravity mead made with a smaller honey-to-water ratio, typically targeting OG 1.030–1.060 and finishing at 4–8% ABV. Named from the French for "water-honey." The sessionable end of the mead style spectrum.
Hydrometer: A weighted, calibrated glass tube that floats at a level indicating specific gravity, the primary instrument used to measure sugar content and track fermentation progress.

I

IBU (International Bitterness Units): The standard scale for a beverage’s hop-derived bitterness, occasionally referenced when adapting beer-style hopping rates to braggot.
Iodophor: An iodine-based, no-rinse sanitiser used at low dilution on equipment before it contacts the must or mead.
Isinglass: A fining agent derived from fish, particularly effective at clearing yeast haze. Not vegan.

K

Kieselsol: A negatively charged, silica-based fining agent, usually used together with chitosan in a two-part clearing system.
Krausen: The foamy, sometimes coloured head of yeast, proteins, and carbon dioxide bubbles that forms on top of an actively fermenting must.
Krupnik: A spiced honey liqueur from Poland and Lithuania, typically made by infusing vodka or a neutral spirit with honey and warming spices rather than through fermentation alone.
Kveik: A group of traditional Norwegian farmhouse yeast strains with unusually high temperature tolerance (up to 40°C for some strains). Voss Kveik is the most commercially available and produces characteristic orange and citrus ester notes at high fermentation temperatures. Valued in meadmaking for extremely fast fermentation timelines.

L

Lag phase: The quiet period immediately after pitching, before visible fermentation activity begins, while yeast acclimatises to the must.
Lees: The sediment that accumulates at the bottom of the fermenter during and after fermentation, consisting of dead yeast cells, honey solids, and precipitated proteins. Racking off lees at the appropriate time prevents autolysis (yeasty, meaty off-flavours) in the finished mead.
LME (Liquid Malt Extract): A syrup form of pre-converted malt sugar used in braggot mode as a fermentable alternative to mashing grain. See DME.

M

Maillard reaction: The browning chemical reaction between sugars and amino acids that occurs during toasting, distinct from the caramelisation used in a bochet.
Malic acid: A sharp-tasting acid naturally present in grapes and some fruits. Certain yeast strains partially metabolise it, softening a must’s acidity.
Malolactic Bacteria: Bacteria that can convert malic acid, or, in an unstabilised mead, potassium sorbate, into compounds that cause off-flavours, most notably the geranium-leaf fault.
Maris Otter: A traditional English pale malt variety, occasionally called for in braggot recipes aiming for classic English brewing character.
Mazer: An archaic term for a meadmaker, derived from the Middle English word for a large drinking cup. Still used in the modern meadmaking community (particularly in competition and hobbyist contexts).
Mead: An alcoholic beverage produced by fermenting honey dissolved in water. The oldest known alcoholic drink. Mead ranges from bone-dry to dessert-sweet, and from still to sparkling, encompassing traditional, fruit (melomel), spiced (metheglin), apple (cyser), caramelised (bochet), and malt (braggot) sub-styles.
Medovukha: A traditional Slavic honey drink with a long history across Russia, Ukraine, and Belarus, often lower in alcohol and less extensively fermented than a modern mead.
Melanoidins: Brown polymer compounds formed by the Maillard reaction, responsible for much of the colour that develops during honey caramelisation.
Melomel: A mead made with the addition of fruit. The fruit contributes fermentable sugar, flavour, colour, and often acidity. Almost any fruit can be used; common examples include raspberry, blackberry, cherry, and blueberry.
Meniscus: The curved surface of a liquid in a narrow tube. Hydrometer and gravity readings are taken at the bottom of the meniscus for accuracy.
Metheglin: A mead made with the addition of spices, herbs, or other botanical adjuncts. Examples range from simple cinnamon-vanilla combinations to complex multi-herb blends inspired by historical recipes.
Midus: A traditional Lithuanian mead, often made with the addition of berry juice.
Morat: A mead made with the addition of mulberries, contributing dark colour and tart fruit character.
Muselet: The twisted wire cage that holds a mushroom-shaped champagne-style cork in place under pressure.
Must: The unfermented or actively fermenting liquid in a batch of mead or wine. In mead, the must is typically honey dissolved in water, potentially with fruit and adjuncts added.

O

Oenomel: An ancient Greek preparation combining honey with unfermented grape juice or must, used both as a drink and in early winemaking and medicinal contexts.
OG (Original Gravity): The specific gravity of the must before fermentation begins, measured after all ingredients (honey, fruit, adjuncts) have been combined. OG indicates the total fermentable sugar content and is used to calculate predicted ABV. A typical traditional mead has OG 1.090–1.120.
Omphacomel: A mead made with the addition of verjuice, the tart juice pressed from unripe grapes, contributing acidity in place of the higher acid found in ripe grape juice.
Oxidation: Flavour damage from oxygen exposure after fermentation, producing flat, cardboard-like, or sherry-like off-flavours.
Oxymel: A preparation combining honey and vinegar, historically used as a tonic and medicinal remedy rather than as a fermented drink in most traditional uses.

P

Pectin: A gelling compound present in fruit and grape cell walls that causes a permanent haze if not broken down before or during fermentation. See Pectolase.
Pectolase: Pectic enzyme (also sold as Pectinase). Used to break down pectin in fruit additions, preventing pectin haze in the finished mead and improving juice extraction. Added 24 hours before pitching yeast or at the time of fruit addition to secondary. Essential for high-pectin fruits (apple, blackcurrant, gooseberry, sloe).
pH: A measure of acidity on a logarithmic scale from 0–14. Target must pH for mead is 3.7–4.0. Below 3.2, yeast enzyme activity drops sharply and fermentation stalls. Monitored with a calibrated pH meter; corrected with potassium bicarbonate.
Pitching: The act of adding yeast to the prepared must to begin fermentation.
Półtorak: A graded style of Polish mead made at roughly a 2:1 ratio of honey to water, the highest-gravity of the four traditional Polish mead grades. Recognised as a Traditional Speciality Guaranteed (TSG) product under EU law. See Dwójniak, Trójniak, and Czwórniak.
Potassium bicarbonate: An alkaline buffering agent used to raise a must’s pH when it drops too low, most often needed with high-acid fruit or forest and eucalyptus honeys.
Potassium metabisulphite (K-meta): The chemical compound sold as Campden tablets, most often called by this name when combined with potassium sorbate to stabilise a mead before back-sweetening. See Campden.
Potassium sorbate: A stabiliser that prevents yeast cells from reproducing, used alongside sulfite to stop a stabilised mead from re-fermenting after back-sweetening. Does not kill existing yeast outright.
PPM: Parts per million. The standard unit for expressing small concentrations in meadmaking — YAN requirement, nutrient doses, sulphite additions. Equivalent to milligrams per litre (mg/L) in water-based solutions.
Pressed only: A pyment-making choice in which grapes are pressed before fermentation so only the juice is used, without skin or pulp contact. See Crushed must.
Priming sugar: Sugar added at bottling time so residual yeast can carbonate a sealed bottle through a small secondary fermentation.
Punch-down: Manually pushing a fruit cap (floating solids) back into the liquid to ensure good extraction and prevent acetobacter growth on the exposed surface. Required for primary ferments with whole fruit additions.
Pyment: A mead made with grapes or grape juice in place of or alongside water, contributing tannin, acidity, and colour a plain mead lacks. A spiced version is called Hippocras. See Hippocras.

R

Racking: Siphoning or pumping mead from one vessel to another, leaving lees behind. The primary reasons to rack are: moving from primary to secondary fermentation, removing from a fruit cap, and clarifying before packaging. Over-racking introduces oxygen and should be avoided in late fermentation.
Racking wand (cane): A rigid tube attached to racking tubing that helps direct the siphon away from sediment when transferring mead between vessels.
Refractometer: An instrument that reads Brix from a few drops of liquid. Convenient for pre-fermentation must but unreliable once alcohol is present.
Rhodomel: A mead flavoured with rose petals or rosehips, contributing floral aroma and, when rosehips are used, added tartness.
Roasted malt: A dark-roasted malt used in small amounts in braggot for colour and roasted, coffee-like character.
Ropiness: A viscous, rope-like texture caused by lactic acid bacteria contamination, one of the rarer mead spoilage faults.

S

Sack mead: A high-gravity, high-ABV mead style, traditionally aged for an extended period to allow the higher alcohol content to mellow before drinking. The name echoes historical "sack" wines, a term applied to fortified or high-strength wine styles such as sherry.
Short mead (session mead): A low-gravity mead intended to be ready to drink within a few weeks rather than months, prioritising a short fermentation and conditioning time over higher alcohol or extended ageing.
Sima: A low-alcohol Finnish fermented drink traditionally made for the Vappu (May Day) festival. Recipes vary: some are brewed with honey, making them a true mead, while others substitute sugar and lemon and are not technically mead at all.
SNA (Staggered Nutrient Addition): A general term for any protocol that divides the total nutrient requirement across multiple additions during early fermentation, rather than adding all nutrients at once. TOSCA 2.0, TOSNA, and TiOSNA are all SNA protocols.
Sparging: Rinsing the spent grain bed with hot water to collect the remaining sugars, a step in all-grain brewing occasionally referenced for braggot.
Sparkling mead: Mead with dissolved CO₂ producing carbonation, either naturally (bottle conditioning with residual or added sugar) or forced (kegging with CO₂). Requires tolerance for approximately 2–3 volumes of CO₂ and appropriate packaging pressure.
Sparkolloid: A polysaccharide-based fining agent used as a follow-up treatment on hazes that resist other fining agents.
Specific Gravity: The ratio of the density of a liquid to the density of pure water at the same temperature. Pure water = 1.000. Honey must at OG 1.110 is 11% denser than water. Measured with a hydrometer (sample drawn) or refractometer (a few drops).
Stall (fermentation): When active fermentation stops before reaching the target final gravity, leaving residual fermentable sugar. Common causes: nutrient deficiency, pH too low, temperature too cold, yeast ABV tolerance exceeded, or fructose accumulation in non-fructophilic yeast with high-F:G honey.

T

Tej: A traditional Ethiopian and Eritrean honey wine fermented with gesho, a flowering shrub whose leaves and bark provide bitterness and act as a natural preservative in place of hops.
Temperature correction: Adjusting a hydrometer gravity reading to account for the sample’s temperature differing from the hydrometer’s calibration temperature, usually 20°C.
Terpenes: Aromatic compounds naturally present in honey that certain yeast enzymes can release, enhancing floral aroma.
Terroir: The concept that a honey’s character reflects the specific place, climate, and forage conditions it was produced in.
TiOSNA: Time and Organic Staggered Nutrient Addition. A hybrid nutrient protocol combining time-based early additions with a final addition timed to the 1/3 sugar break measured by hydrometer. More complex than TOSCA 2.0.
Top-up: Adding water to a batch after fermentation to correct for evaporation or an over-concentrated must, diluting gravity, ABV, and other measured values proportionally.
TOSCA 2.0: Time-based Organic Staggered Compound Addition. The current best-practice nutrient protocol, using four time-based additions (24h, 48h, 72h, 96h after pitch) plus GoFerm PE at rehydration. No gravity measurements required. See the TOSCA 2.0 guide for full details.
TOSNA: Time-Organic Staggered Nutrient Addition. An older gravity-based SNA protocol where additions are triggered by Brix or specific gravity milestones rather than hours. Effective but requires a hydrometer for accurate timing.
Traditional mead: A mead made from honey, water, and yeast only — no fruit, spices, or other adjuncts. The character comes entirely from the honey variety and fermentation management. Sometimes called "show mead" in competition contexts.
Trial jar: The narrow jar a hydrometer sample is drawn into for taking a reading.
Trójniak: A graded style of Polish mead made at roughly a 1:2 ratio of honey to water. Recognised as a Traditional Speciality Guaranteed (TSG) product under EU law. See Półtorak, Dwójniak, and Czwórniak.

W

Wine thief: A tube used to draw a small sample of mead out of a carboy without disturbing the rest of the batch.
Wine whip: A whisk-shaped drill attachment used to aerate or degas a must quickly.
Wort: The sugar-rich liquid extracted from mashing grain, before fermentation begins. The malt equivalent of honey must.

X

Xylitol: A non-fermentable sugar alcohol used to back-sweeten a mead with no risk of triggering renewed fermentation. Toxic to dogs, so requires careful handling and storage.

Y

YAN: Yeast Assimilable Nitrogen. The fraction of total nitrogen in the must that yeast can metabolise for growth and fermentation. Measured in ppm (mg/L). The required YAN is calculated from sugar concentration and yeast nitrogen demand. Insufficient YAN causes H2S, stalls, and off-flavours.
Yeast nutrient: A general term for products that supply yeast with the nitrogen, vitamins, and micronutrients absent from honey. Specific products include GoFerm PE (rehydration), Fermaid O (organic nitrogen), Fermaid K (blended), and DAP (inorganic nitrogen). Generic yeast nutrient blends from homebrew retailers vary widely in composition.