The vinegar acid. A trace can read as pleasant sharpness; a lot of it is a fault. It forms during fermentation and roasting. A cup that smells of vinegar usually means the processing ran too far, and cuppers mark that as a defect rather than as acidity.
Acidity
The pleasant tang in coffee: bright and juicy, like fruit — not sour like vinegar. It shows most in lighter roasts and high-grown coffees. Sourness with no sweetness behind it is a different thing: usually under-extraction.
Agitation
Anything that stirs coffee while it brews — a spoon, a swirl, a hard pour. More agitation extracts faster. It helps every grain get wet and give up its flavor evenly. Too much of it in a paper cone drives the finest particles down into the filter, which clogs and stalls the brew.
Altitude
How high the coffee grew, in metres above sea level (masl). Higher usually means a denser, brighter coffee. Cooler air slows ripening, so the seed packs in more sugar and acid. Read it next to the country: near the equator, the same chill needs more height.
Americano
Espresso topped up with hot water. No milk.
Anaerobic fermentation
Fermenting coffee in sealed tanks or bags with the air shut out, so different microbes shape the flavor. One of a family of experimental processes. Carbonic maceration, borrowed from Beaujolais winemaking, ferments whole cherries under carbon dioxide. The cups can be winey, boozy and very fruity: striking or divisive, and often both. Roasters tend to say so on the bag.
Arabica
The species behind most specialty coffee: sweeter and more complex than robusta, with less caffeine. It is fussier to grow — it likes altitude, mild temperatures and shade — and more exposed to disease, which is why it costs more.
Aroma
What you smell. Most of what you call a coffee’s taste reaches you through your nose.
Astringency
A dry, rough, puckering feel, like strong black tea. Something you feel rather than taste. Largely caused by compounds that strip the slippery layer of saliva, so your tongue drags. It often arrives with bitterness in an over-brewed cup, but the two are separate signals: one is felt, the other tasted.
Bar (pressure)
A unit of pressure. One bar is roughly the air pressure around you at sea level; espresso brews at about 9. Brewers are often compared in bars above the air around them: an espresso machine about 9, a moka pot roughly 1–1.5, a hand-pressed AeroPress about 0.25–0.5. A pump rated for 15 or 20 bar is describing its ceiling; tests and café practice still settle around 9.
Barista
The person behind the café counter making the coffee — and usually the best person to ask about the beans.
Bean belt
The band of the tropics, between the Tropics of Cancer and Capricorn, where coffee grows.
Bitterness
Part of what makes coffee taste like coffee. Harsh and drying means there is too much of it.
Blend
Coffees from more than one origin mixed together, usually for a steady, balanced cup all year.
Bloom
The first small pour that wets the grounds and lets trapped CO2 bubble out before the main brew. Use about two to three times the coffee’s weight in water, stir or swirl so nothing stays dry, and wait 30–45 seconds. Fresh coffee and darker roasts bloom big; old or pre-ground coffee barely moves, because most of its gas has already gone.
Body
How heavy the coffee feels in your mouth: skim milk against whole milk. Oils and fine particles add it, so a French press is heavy and a paper-filtered cup is light.
Brew ratio
Coffee to water, by weight. At 1:15 you use 15 g of water for every gram of coffee. Most filter coffee lands between 1:15 and 1:17. Espresso is written differently — coffee to the drink in the cup — and runs far stronger, around 1:2.
Brew temperature
How hot the water is when it meets the coffee — 90–96°C for most brewing. Hotter water pulls flavor out faster. Off the boil, a thirty-second wait lands you in the window.
C price
The benchmark futures price for arabica on the ICE exchange, in US cents per pound. Each contract covers 37,500 pounds of washed arabica. Physical coffee usually trades at the C price plus or minus a differential for origin and quality. It swings with Brazilian harvests, stockpiles, trade politics and speculation: about 87 cents a pound at its 2019 low, above $4.30 in early 2025.
Cappuccino
Espresso, steamed milk and a thick cap of airy foam — roughly a third each.
Channeling
Water finding a shortcut through the puck, so part of the coffee over-extracts and the rest under-extracts. It tastes sour and bitter at once, and the shot often runs fast. A bottomless portafilter shows it as spurts. The fixes are in the prep — a steady dose, clumps broken up, a level tamp — rather than in grinding finer.
Chicory
The roasted, ground root of the chicory plant, blended into coffee for body, a dark color and a bitter edge. It has no caffeine. It first went into coffee to stretch it when coffee was scarce or dear, and stayed for the taste. South Indian filter blends carry anywhere from about 10% to 40% chicory; India’s food rules call for at least 51% coffee in a coffee-chicory mix.
Citric acid
The lemon-and-orange acid. In coffee it reads as zesty, citrus brightness. In a 2023 study it was the one acid in brewed coffee sitting clearly above what tasters can detect on its own. It fades as roasts get darker, so light roasts show the most of it.
Cloth filter
A fabric filter that stops most fines but lets some oils through — body and clarity at once. The heart of Japanese nel drip. It rewards care: rinse it after brewing, keep it in water in the fridge, never use soap, and replace it once it stops smelling clean. A neglected cloth makes musty coffee.
Coffee cherry
The fruit of the coffee tree. What we call beans are its seeds — usually two to a cherry, face to face. It ripens from green to red (or yellow, in some varieties) over months, and only the ripe ones make a sweet cup — which is why careful farms pick by hand.
Cold brew
Coffee steeped in cold or room-temperature water for many hours and never heated. Smooth, sweet, gentle. Coarse grounds, 12–24 hours, usually brewed strong and diluted. Its pH is close to hot coffee’s, but it carries fewer of the acids you taste as brightness. Because it is never heated, steep it in the fridge and finish it within about a week.
Concentrate
Coffee brewed extra strong on purpose, to be diluted with water, milk or ice before you drink it. Cold brew is the usual example, brewed at anywhere from about 1:4 to 1:8 and diluted to taste — roughly 1:1 for a 1:8 brew. Straight from the jar, it is a lot of coffee in a small glass.
Cortado
Espresso cut with about as much warm milk.
Crema
The tan foam on an espresso: gas from roasting, fizzing out of the shot and held up by the coffee’s oils and solids. Fresh beans make more of it, robusta makes more than arabica (though arabica’s lasts longer), and double-walled home baskets can whip it up from almost anything. It looks like a quality stamp. It isn’t one — taste decides. Because it is foam, it also makes millilitres a poor way to measure a shot.
Crust
The raft of wet grounds that floats on a steeping brew. Breaking it lets the grounds sink.
Cupping
How professionals taste coffee: grounds steeped in a cup, the crust broken, then slurped from a spoon. Every sample gets identical treatment — 8.25 g to 150 ml, water about 93°C, the crust broken at about four minutes, tasting from about 70°C — so the differences you taste come from the beans, not the brewing.
Decaf
Coffee with most of its caffeine removed — about 97% — before roasting. Water, carbon dioxide or a solvent does the removing; the good processes leave the flavor largely alone. It stales as fast as any coffee.
Degassing
Freshly roasted coffee giving off carbon dioxide — why beans want a few days’ rest before brewing. Gas escaping as you brew pushes water away from the grounds, so very fresh coffee brews unevenly. It is also why fresh grounds bubble when the water hits them.
Dialing in
Changing one thing at a time — grind, ratio, temperature, time — until a coffee tastes right.
Direct trade
Buying straight from a known farm or co-op, often with a quality premium: a roaster’s claim, not a certificate. No single standard defines it, so what it means varies by roaster, and critics point to the lack of outside checks. The convincing versions name the farm, publish the price paid and last for years. Treat the phrase as a question to ask, not an answer.
Drawdown
The end of a pour-over, when the last of the water drains through the bed — and the time that takes. A handy clue before you even taste. For a one-cup cone, most recipes finish around 2½ to 4 minutes, all in. Much faster usually means sour: grind finer. Much slower usually means bitter or a clogged filter: grind coarser and pour more gently.
Espresso
A small, concentrated coffee made by forcing hot water through finely ground coffee under pressure.
Extraction
What the water dissolves out of the grounds. Too little tastes sour and thin; too much, bitter and drying. Grind, time and temperature move it; the ratio mostly moves strength instead.
Fair Trade
Certification that guarantees farmer co-ops a minimum price, plus a premium to invest together. Fairtrade International’s floor for washed arabica was about $1.80 a pound at the time of writing, rising to $2.00 from 1 December 2026, with a 20-cent premium on top. When the market price is higher, co-ops get the market price and the premium. It is a safety net rather than a price for quality.
Filter kaapi
South India’s everyday coffee: a strong decoction dripped through a two-tier steel filter, then mixed with hot milk and sugar. Fine coffee, often blended with chicory, sits under a press disc in the pierced upper cup, and water just off the boil drips through into the lower cup over about 10–15 minutes. The decoction is cut with roughly 2–4 parts hot milk and poured between a tumbler and a dabarah until it froths.
Fines
The very smallest particles a grinder makes. Every grinder makes some; blade grinders make a lot. Fines give up their flavor fast and add weight to the cup. In a paper cone they can pack into the filter and stall the brew; through a metal mesh they arrive as silt. A better grinder and a gentler pour keep them in check.
Finish
What stays after you swallow: how long the flavor lasts, and whether it’s pleasant. Cupping forms call it aftertaste and score it down when it’s short or unpleasant. Much of it is retronasal smell, so breathe out through your nose to catch it.
First crack
The popcorn-like pop as steam and CO2 pressure split roasting beans: where light roasts begin. It arrives around 190–205°C, depending on the machine and where its probe sits. The time after it is called development; many roasters keep that to very roughly a fifth of the roast. Carry on to about 225°C and second crack begins: quieter, faster crackling, with oils rising to the surface and roast flavors taking over.
Flash brew
Hot coffee brewed straight onto ice, with the ice counted as part of the brew water. A common split is about 60% of the water poured hot and 40% waiting as ice, ground a touch finer because less water meets the grounds. It keeps more of a coffee’s bright side than cold brew does, and it is ready in minutes.
Flat white
A double espresso under a thin layer of glossy microfoam — the coffee still leads.
Flavor wheel
A chart of flavor words laid out from general in the middle to specific at the rim. The best-known is the SCA and World Coffee Research Coffee Taster’s Flavor Wheel (2016), built on a sensory lexicon of 110 attributes, each with a reference. This app’s wheel groups its notes into seven families.
Gooseneck kettle
A kettle with a long, thin, curved spout that pours a slow, steady stream you can aim. It only matters for pour-over, where it matters a lot: a controlled stream of a few grams a second wets the bed evenly without digging a crater. An ordinary kettle can do the job, just less politely.
Green coffee
Coffee seeds after processing and drying, before roasting: pale, hard and grassy-smelling. It keeps for months if dry and cool, where roasted coffee fades in weeks. Everything you taste as coffee is still to be made by the roast.
Grind size
How fine the coffee is ground. Finer grounds give up their flavor faster; coarser ones, slower. Match it to the brew time: coarse for a long steep like a French press, fine for a fast one like espresso.
Honey process
The skin comes off but some of the sticky fruit stays on while the seeds dry — sweet, and in between washed and natural.
Immersion
Brewing with the coffee steeping in all of its water at once, as in a French press or a mug. Contact time does the work, so it forgives an uneven pour — the reason it is the first way to learn.
Latte
Espresso under plenty of steamed milk and a thin layer of foam — the mildest of the milk drinks.
Leaf rust
A fungus that spots coffee leaves yellow-orange and makes them fall: the most damaging disease of arabica. Caused by Hemileia vastatrix. From 1869 it destroyed Ceylon’s coffee, and it hit Colombia and Central America hard between 2008 and 2013. Most resistance in arabica comes from robusta genes carried by the Timor Hybrid, parent of the Catimors and Sarchimors. The fungus keeps evolving, so some once-resistant varieties no longer are.
Lungo
A long espresso, about 1:3 by weight: lighter and clearer, with a little more bitterness. More water through the same coffee extracts more and dilutes it, so body drops and clarity rises. Not the same as an americano, which is a normal shot topped up with hot water.
Macchiato
An espresso “marked” with a spoonful of milk foam.
Maillard reaction
Browning between sugars and amino acids in the heat: the reaction behind toast and much of coffee’s aroma. In a roaster it gets going from roughly 150°C, turning yellow beans brown and building hundreds of aroma compounds. It overlaps with caramelization, where sugars break down on their own at slightly higher heat. How long a roaster lets this stage run changes the cup.
Malic acid
The green-apple acid: crisp and tart. Often credited for the snap in Kenyan coffees. Most of an apple’s sourness is malic acid, which is why tasters reach for “green apple” or “pear” when they meet this kind of brightness. Like citric acid, it drops as roasting goes on.
Metal filter
A steel mesh, as in a French press, that lets oils and some fines through: a heavier cup with a little silt. Reusable and never papery, but the oils it passes also cling to it and turn rancid, so it needs a proper wash. French press coffee keeps most of its cafestol, the oil a paper filter would have caught.
Microfoam
Steamed milk with bubbles too small to see: glossy, pourable, the base of a flat white and of latte art.
Moka pot
A stovetop brewer that pushes water up through coffee using pressure from its heated base — roughly 1–1.5 bar. Alfonso Bialetti’s 1933 design is still the classic. The cup is strong and heavy, but not espresso. Use water just off the boil, a fine grind a notch coarser than espresso, no tamp, medium-low heat and the lid up, and stop before it sputters.
Monsooned
Natural coffee left in open-sided warehouses on India’s Malabar coast through the monsoon, until the beans swell, pale and lose most of their acidity. In the days of sail, coffee took months to reach Europe from India and arrived swollen, pale and mellow. Faster ships ended that, so the change is now made on land: dry-processed arabica or robusta is spread in open-sided warehouses for about 12–16 weeks of the June–September monsoon, raked, turned and later bagged, until it turns pale gold. The cup is heavy, very low in acid and often spicy.
Mouthfeel
The physical feel of coffee in your mouth: its weight, plus texture such as silky, oily or gritty. The SCA’s newer cupping forms score mouthfeel where the older form said body. Oils, tiny suspended particles and dissolved solids all shape it, which is why the filter you brew through changes it so much.
Mucilage
The sticky, sugary layer between a coffee cherry’s pulp and the parchment around its seed. Rich in pectins and sugars. Washed coffees ferment it off before drying, honey coffees keep some or all of it on while they dry, and naturals dry inside the whole fruit. What happens to it, and to the microbes feeding on it, is much of what “process” means.
Natural
The whole cherry dries around its seeds — fruitier, wilder, berry-forward cups.
Origin
Where the coffee grew: the country, often the region, sometimes the farm. A good first guess at its flavor.
Orthonasal smell
Smelling through your nostrils — sniffing the dry grounds or the cup before you drink. The front route to your smell sensors. Cuppers use it twice: on the dry grounds, which they call the fragrance, and on the wet coffee, the aroma. Its partner, retronasal smell, works from inside your mouth.
Over-extracted
The water pulled too much out: bitter, harsh, drying. Grind coarser, brew shorter or cooler.
Palate fatigue
Your senses dulling with repeated tasting, so each sip reports a little less than the last. Taste and smell both adapt to what they keep meeting. Short sessions, room-temperature water and plain water crackers between cups help, and so does spitting when you cup several coffees.
Paper filter
Filter paper catches nearly all fines and most coffee oils, for a clean, bright, lighter-bodied cup. It also holds back most of the cafestol, a coffee oil that can raise LDL cholesterol. Rinsing it warms the brewer and washes out any papery taste, which matters most with brown, unbleached paper. Brands drain at different speeds, so a new box can shift your brew time.
Parchment
The papery shell around each coffee seed, left on while washed coffee dries and hulled off at the dry mill. Washed coffee dried in it is called parchment coffee, or pergamino, and it usually rests that way before milling. The dry mill hulls it off before the coffee is exported. Beneath it sits a thinner silver skin, which some mills polish away.
Peaberry
A single round seed in a cherry that would usually hold two flat-faced ones. It happens when only one of the two seeds develops, so nothing flattens it. Peaberries are a small share of a crop (around 5% is often quoted) and are sieved or sorted out and sold separately, as in Kenya’s PB grade. Claims that they taste or roast better are debated.
Percolation
Brewing by running water through a bed of coffee and out of the bottom, as a V60, Chemex or drip machine does. Fresh water keeps arriving while brewed coffee leaves, so percolation pulls flavor out more efficiently than a steep — and the grind, by setting how fast the water drains, also sets the contact time. Not to be confused with the old stovetop percolator, which cycles hot coffee back over the same grounds again and again.
Phosphoric acid
A mineral acid — the one in cola. Tasters link it to a sparkling edge, though its role in coffee is debated. Long credited for the fizz in Kenyan coffees, on thin evidence: robusta tends to carry more of it without tasting brighter, and a 2023 study found it only just above what tasters can detect. Malic acid may deserve the credit.
Portafilter
The handle that locks into an espresso machine, holding a metal basket of ground coffee. Baskets are made for a dose: an 18 g basket wants about 17–19 g. Double-walled (pressurised) baskets on many home machines add back-pressure so even pre-ground coffee pours; plain single-walled baskets rely on your grind and puck prep. A bottomless portafilter has no spouts, so you can watch the coffee leave the basket.
Pour-over
Brewing by pouring water by hand over coffee in a filter cone — the V60 and the Chemex are the classics. A percolation brew you steer with the kettle: where you pour, how fast and from how high all change how evenly the coffee gets wet. That control is the appeal, and the reason it forgives less than a steep.
Process
How the fruit is removed and the seed dried after picking — washed, natural or honey. Two coffees from the same farm can taste worlds apart on this alone.
Puck
The bed of ground coffee in an espresso basket — and the damp disc you knock out afterwards. Water under pressure takes the easiest route through it, so an even puck is the whole point of puck prep: a steady dose, clumps broken up, a level tamp. The spent puck says less than people think; taste the shot instead.
Pulse pour
Adding the brew water in several smaller pours with pauses between, instead of one continuous stream. Each new pour stirs the bed again and the water level rises and falls, which makes the brew easy to steer. A single slow pour keeps the bed calmer. Both work; switching between them changes your recipe.
Retronasal smell
Aroma travelling from the back of your mouth up to your nose as you sip, swallow and breathe out. The back route to the same smell sensors, and the reason flavor feels as if it happens in your mouth. Fruit, flowers and caramel arrive this way. Pinch your nose and they stop; slurping and breathing out through your nose turn them up.
Ristretto
A short espresso, roughly 1:1 to 1:1.5 by weight: thick, heavy and intense. Less water through the same coffee gives a stronger, more syrupy shot that has pulled a little less out. If one tastes sour, grind a touch finer, or let it run a little longer.
Roast date
The day the coffee was roasted — the date that matters. Most beans are at their best from about 4 days to 4 weeks after it. A “best by” date a year away tells you little. Good roasters print the roast date.
Roasting
Heating green coffee until hundreds of reactions turn it brown and build the flavors you know as coffee. Lighter roasts keep more of the bean’s own fruit and acidity; darker ones trade them for roasty, bittersweet flavors.
Robusta
The hardier, cheaper species: harsher in the cup, with roughly twice the caffeine of arabica. It grows lower and hotter and shrugs off pests, so it fills a lot of instant coffee — and some espresso blends use it on purpose, for kick and a thick crema.
Scalded milk
Milk heated until it tastes cooked. Cooks mean about 80°C; baristas use it for anything steamed much past 70°C. Past about 70°C some milk proteins start to change, and flat, faintly eggy flavors creep in. For drinks, aim for about 55–65°C. In the kitchen, scalding is sometimes the point: older bread and white-sauce recipes ask for it.
Selective picking
Harvesting only ripe cherries, by hand, returning to the same trees every eight to ten days. Cherries on one branch ripen at different times, so pickers make several passes through a season. It costs more than strip-picking, which takes everything off the branch in one go, ripe or not (by machine on big, flat farms in places like Brazil), and leaves the unripe fruit to be sorted out later.
SHB
Strictly hard bean: a Central American label for coffee grown high, where it ripens slowly and dense.
Single origin
Coffee from one place — a country at the loosest, a single farm or lot at the most exact.
Slurping
Drawing coffee in with air, loudly, so it coats your whole mouth and its aroma reaches your nose.
Specialty grade
Green coffee with no serious defects, only a handful of minor ones, and a cup that stands out. Graders count defects in a few hundred grams of green coffee and then cup it. For decades “specialty” also meant 80 or more on the SCA’s 100-point form, scored by licensed Q graders. The SCA’s newer Coffee Value Assessment adds descriptive and other assessments instead of leaning on one number, and the SCA has run the Q program since 2025.
Strength
How concentrated the brew is, set mostly by the ratio. Weak is not the same as under-extracted. A weak but balanced cup wants more coffee; a sour one wants more extraction.
Stretching
The first part of steaming: the tip sits just under the surface, pulling air into cold milk with a paper-tearing hiss. A second or two is enough for a flat white or latte on a café machine; a cappuccino wants a few more, and small home machines take longer. Finish before the milk reaches body temperature, then switch to texturing.
Sweetness
The round, pleasant taste of a well-grown, well-roasted coffee — with nothing added.
Tamping
Pressing the ground coffee in the basket into a flat, even bed before brewing. Level matters far more than force: tests have found a harder tamp changes little, while a tilted one leaves a thin side for the water to find. Moka pots are never tamped.
Texturing
The second part of steaming: the tip goes a little deeper and the milk spins, folding big bubbles into microfoam. The whirlpool heats the milk evenly and breaks the air from stretching into bubbles too small to see. Carry on to about 60°C, then wipe and purge the wand, tap the jug and swirl until the milk looks like wet paint.
The break
Pushing a spoon through the crust of a cupping bowl, about four minutes in, to release a burst of aroma. The standard allows three to five minutes. Keep your nose close, stir three times, then skim off the foam and floating grounds before anyone tastes.
Triangle test
Three cups, two the same and one different: pick the odd one. A pure guess is right a third of the time. A standard sensory test (ISO 4120), and one coffee tasters train and sit exams on. You must choose even when unsure, so results can be checked against chance: five right out of six is very unlikely to be luck.
Under-extracted
The water pulled too little out: sour, thin, sometimes salty. Grind finer, brew longer or hotter.
Variety
A cultivated line within a species. Typica, Bourbon, SL28 and Gesha are all varieties of arabica. Growers choose varieties for yield, height, disease resistance and cup quality, and rarely get all four. “Varietal” is often used for the same thing. Most arabica grown outside Ethiopia descends from two lines taken out of Yemen, Typica and Bourbon; the rest includes Ethiopian landraces such as Gesha and hybrids bred to resist leaf rust.
Washed
The fruit is stripped off before the seeds dry — clean, crisp cups that taste of where they grew.
WDT
Stirring the grounds in the basket with very thin needles to break up clumps before tamping. Named for John Weiss, who shared it on a home-espresso forum in December 2005, using a single dissecting needle. Modern tools hold several needles well under a millimetre thick. It evens out the bed, so the water has no loose patch to rush through.
Wet-hulled
Indonesia’s method: parchment is hulled off while the bean is still damp, then the naked bean dries. Used by most small farmers in Sumatra, Sulawesi, Flores and Papua, where rain makes long drying risky and hulling early gets coffee sold sooner. The finished beans look bluish green, and the cups tend to be heavy-bodied, low in acidity and often earthy.
Whole bean
Coffee sold unground. It keeps its aroma far longer than pre-ground — grind it just before you brew.
Yield
The weight of espresso in the cup. With the dose going in, it sets the ratio: 18 g in, 36 g out is 1:2. Weigh it rather than reading millilitres: crema is foam, so volume swings with the beans. Not to be confused with extraction yield, the share of the coffee that dissolved.