Glossary
The vocabulary specialty coffee actually uses. Each term is one short page — what it means, why it shows up, and what it changes about the cup. No long essays; if a term needs a full article, it lives in another section and this one points at it.
Articles
51- Astringency A drying, puckering sensation on the tongue and inner cheeks — the same feeling unripe persimmon or strong black tea leaves behind. It's not bitterness and it's not acidity. It's a tactile flaw, not a taste, caused by polyphenols binding to the proteins in your saliva. Intro 1 min
- Bypass Water that reaches your cup without passing through the coffee bed. In a pour-over, that's water poured against the wall of the dripper that runs straight down the filter, never touching the slurry — diluting the brewed coffee on its way through. Intro 1 min
- Slurry The wet bed of coffee grounds and water sitting in the brewer during a pour-over. Not the dry coffee, not the brewed liquid below the filter — the muddy, swirling middle. Intro 1 min
- Gooseneck kettle A kettle with a long, narrow, S-curved spout that lets you pour a thin, controlled stream of water exactly where you aim it. The shape borrows its name from the bird — the spout rises from the body, bends forward, and tapers like a goose's neck. Intro 1 min
- WDT (Weiss Distribution Technique) A pre-brew step where you stir the dry coffee bed with a thin tool — a needle, a fine wire, an unbent paperclip — to break up clumps before water touches it. Named for John Weiss, the espresso enthusiast who popularized it as a way to fix uneven distribution in portafilters. Intro 1 min
- Extraction The act of dissolving compounds out of ground coffee into water. Roasted coffee is about 30 % soluble — the maximum mass that water can theoretically pull out before what's left is just dry cellulose. Specialty filter brewing aims for 18–22 % of that mass actually extracted, the window where the cup is balanced. Intro 1 min
- Strength How concentrated the brewed coffee is — measured as TDS (total dissolved solids), the percentage of dissolved coffee mass per gram of liquid in your cup. A typical filter coffee lands between 1.20 % and 1.50 % TDS. Espresso lives at 8–12 %. Intro 1 min
- TDS (Total Dissolved Solids) The percentage of dissolved coffee mass per gram of liquid in your brewed cup. 1.30 % TDS means 1.3 grams of coffee compounds are dissolved in every 100 grams of liquid. It's the number that quantifies what your tongue calls "strength." Intermediate 1 min
- Immersion brewing A brewing approach where the ground coffee sits fully submerged in water for a defined time before the liquid is separated from the bed. The opposite of percolation, where water passes through the bed continuously. Intro 1 min
- Percolation brewing A brewing approach where water passes through the coffee bed continuously and exits as brewed liquid almost immediately. Every pour-over method is percolation: V60, Chemex, Kalita, Origami, Orea, Tricolate. Espresso is also percolation, just under nine bars of pressure. Intro 1 min
- Muddying A specific over-extraction symptom where the cup loses clarity and tastes thick, dull, and undifferentiated. Acidity collapses, the aromatics that should be sitting on top go quiet, and what's left is heavy roast and cardboard. The bean stops sounding like itself. Intro 1 min
- Fines The smallest particles produced when you grind coffee — typically below 100 microns. Every grinder produces fines, even the best ones. The question isn't whether they exist; it's how many you get and how evenly they're distributed across the bed. Intro 1 min
- Boulders The largest particles in a ground coffee bed — informal name for the chunks that didn't get fully broken down by the burrs. The opposite of fines. Visible to the naked eye in most home grinds: little gravelly bits sitting alongside the medium particles. Intro 1 min
- Burrs The two cutting wheels inside a coffee grinder that fracture beans into a target particle size. They sit very close together, the gap calibrated to fractions of a millimeter, and the bean has to pass between them to come out the other side as ground coffee. Intro 1 min
- Degassing The release of CO₂ trapped inside roasted coffee beans. Roasting produces gas as a by-product of the Maillard reaction; that gas slowly escapes through the bean's cell structure over the days and weeks after roast. Coffee is "degassing" the entire time it sits in the bag. Intro 1 min
- Off-roast The number of days that have passed since a coffee was roasted. Specialty bags often print a roast date instead of an expiry date, and a coffee at "day 14 off-roast" was roasted exactly two weeks ago. Intro 1 min
- Clarity A cup attribute that describes how distinctly the individual flavors come through. A clear cup lets you taste each note as a separate thing — citrus and florals and malt and finish — instead of one homogeneous brown blur. The opposite of muddied. Intro 1 min
- Body The tactile weight of coffee in your mouth — what makes one cup feel like skim milk and another feel like cream. Body is independent from flavor and from strength; you can have a strong, light-bodied cup and a weak, heavy-bodied one. Intro 1 min
- Acidity The bright, lively quality in a coffee that makes you salivate — analogous to the acidity in a green apple, a citrus fruit, or a glass of crisp white wine. In specialty coffee, acidity is a virtue, not a flaw. It's what separates a cup that tastes alive from one that tastes flat. Intro 1 min
- First crack The audible pop a coffee bean makes during roasting when its internal moisture flashes to steam and forces its way out, fracturing the bean structure. A sharp, distinct pop — popcorn is the comparison every roaster uses, and it holds. Happens around 196–205 °C bean temperature, depending on the bean and the roaster. Intro 1 min
- Second crack A second audible cracking event during roasting, around 224–230 °C bean temperature, when the bean's cellulose structure breaks down further and oils start to migrate to the surface. The sound is quieter than first crack but faster and denser — a fine, continuous crackle rather than a series of distinct pops, closer to cereal in milk. Intro 1 min
- Roast defects Specific flavor faults that come from how a coffee was roasted, not from the green bean itself. Recognizable by their consistency: every bag from a roaster who's making the same mistake will share the same defect, no matter the origin. Intro 1 min
- Green defects Faults present in the unroasted (green) coffee bean that no roast can rescue. Specialty grading systems exist precisely to count these — Q-grade and SCA both score a coffee partly by how few defects it contains per kilo. Intro 1 min
- Siphon (vacuum pot) A two-chamber brewer that uses heat-driven vapour pressure to push water up into the coffee, then a vacuum to pull the finished brew back down through a filter. Also spelled syphon, and called a vacuum pot in older writing. Intro 1 min
- Refractometer A small handheld device that measures the refractive index of brewed coffee — how much the liquid bends light — and converts that into a TDS percentage. Plug TDS, brew water, and dose into an extraction calculator and you get the extraction yield: the percentage of bean mass that actually dissolved into your cup. Intermediate 1 min
- Bypass ratio Putting a number on bypass: the percentage of total brew water that didn't pass through the coffee bed — water that fell down the side of the filter, or water added directly to the served cup, never touching the slurry. A 0 % bypass brew has every drop interact with the grounds. A 30 % bypass brew has 30 % of its water arrive at the cup as plain hot water that just dilutes the rest. Intermediate 2 min
- Specialty coffee A category — not just a marketing label — defined by a measurable cup score. The Specialty Coffee Association sets the threshold: a coffee that scores 80 or above on the 100-point cupping scale can call itself specialty. Below 80, it's commercial. Intro 1 min
- Third-wave coffee The cultural and commercial movement that re-positioned coffee from a commodity drink into a craft product, beginning roughly in the late 1990s and crystallizing through the 2000s. The name borrows from beer and food culture, where each "wave" describes a similar shift toward provenance and quality. Intro 1 min
- Pulse pour A pour-over technique where you split the total water into multiple discrete pours separated by short pauses. The bed is allowed to drain partially between each pulse — water level drops to roughly the top of the slurry — and then you pour again. Common shapes: 4 pulses, 5 pulses, sometimes 6. Intro 1 min
- Continuous pour A pour-over technique where, after the bloom, you maintain a single steady stream of water onto the bed without stopping until the target weight is reached. The opposite of a pulse pour. The water level above the slurry is allowed to rise and stabilize, then drain through together at the end. Intro 1 min
- Swirl A specific agitation technique where you grip the brewer (or its server) and rotate it in a quick circular motion to redistribute the slurry without breaking up the bed structure. Most commonly used right after the bloom or after each pour in a pulse-pour recipe. Intro 1 min
- Pre-infusion A short initial water contact phase before the main extraction begins. The grounds are wetted with a small amount of water, then allowed to sit briefly so they can absorb water, swell, and release CO₂ before the bulk of the brew water arrives. Intro 1 min
- Puck The disc of spent grounds left in the brewer at the end of a brew. The word comes from espresso — where the compacted, wet hockey-puck-shaped cake of grounds is the literal physical object you knock out of the portafilter — but it's now used for filter coffee too. Intro 2 min
- Tasting note A short descriptor on a coffee bag — "blueberry, dark chocolate, brown sugar" — meant to tell you what flavors you should expect to find in the cup. Roasters write them based on cuppings of that specific lot. They're a prediction, not a guarantee, and they read better as a vocabulary scaffold than as a literal taste menu. Intro 1 min
- Varietals The botanical varieties of Coffea arabica — like grape varieties for wine, or apple varieties for cider. Two coffees from the same farm, processed the same way, will taste different if they're different varietals. Specialty bags often print the variety alongside origin and processing. Intro 1 min
- Elevation The altitude (in metres above sea level, MASL) at which a coffee was grown. Specialty bags routinely print this — "1,800 MASL," "1,950 MASL" — because elevation is one of the strongest predictors of cup quality in arabica. Intro 1 min
- Water activity A measurement of the available water inside a coffee bean — water free enough to participate in chemical reactions, microbial growth, and aroma loss. Written Aw, on a scale from 0 to 1 where 1 is pure liquid water and 0 is bone dry. Advanced 1 min
- Single origin Coffee that comes from one identifiable place. The exact precision of "one place" varies by usage: Intro 1 min
- Blend Coffee made by combining beans from two or more origins, varieties, or roast curves into a single bag. The opposite of single origin. Done well, blending creates a cup that's larger than its parts — sweetness from one component, body from another, brightness from a third. Done poorly, it's a way to hide low-quality coffee inside a more interesting one. Intro 1 min
- Microlot A small, separately-processed batch of coffee from a single farm — typically a few hundred kilos at most — kept apart from the farm's larger production because it's expected to score higher in cup quality. Microlots are the way specialty roasters access the most distinctive coffees a producing region has to offer. Intro 1 min
- Dose The amount of dry coffee — measured by weight in grams — that you put into the brewer for a single brew. The starting point of every recipe. "Use a 15 g dose" means you'll grind 15 grams of beans before water touches anything. Intro 1 min
- Direct trade A sourcing model in which a roaster buys green coffee directly from the producer — farm, cooperative, or producer group — without commodity-market intermediaries setting price or terms. The roaster typically visits the farm, knows the producer's name, and negotiates a price tied to cup quality rather than to the C-market. Intro 2 min
- Fair Trade A certification standard that guarantees a minimum price floor for green coffee, regardless of where the C-market futures price sits. Created in the late 1980s, formalized by Fairtrade International in 1997, and now visible on most supermarket coffee shelves through the round Fairtrade Mark. Intro 1 min
- Decaf (decaffeinated coffee) Coffee beans that have had ~97-99% of their caffeine removed before roasting. The bean still tastes like coffee — most of the flavour compounds aren't caffeine — but it won't keep you up at night. Specialty decaf has gotten dramatically better in the last decade as the decaffeination processes have improved. Intro 2 min
- Crema The reddish-brown layer of foam that sits on top of a freshly pulled espresso shot. Made of CO₂ trapped inside a colloidal suspension of microscopic coffee oils, melanoidins, and dissolved compounds. Crema only happens under pressure — pour-over and immersion brews don't produce it because they don't extract under nine bars. Intro 2 min
- Portafilter The metal-handled basket-holder that locks into an espresso machine's group head. The barista grinds coffee into the basket, tamps it, locks the portafilter into the machine, and water is forced through under pressure to make espresso. Without a portafilter, an espresso machine is just a kettle. Intro 1 min
- Tamping The act of pressing ground coffee in an espresso portafilter into a flat, level, evenly compacted puck before locking the portafilter into the machine. Without tamping, the bed has air gaps and uneven density; pressurized water finds the path of least resistance, channels through, and extracts unevenly. Intro 1 min
- Hand grinder (manual grinder) A coffee grinder powered by a hand crank rather than an electric motor. Pour a dose into the hopper, twist a knob to set grind size, attach the crank, and spin until the chamber is empty. Specialty hand grinders use the same conical or flat burrs as electric models — they're not a compromise on grind quality, only on speed and effort. Intro 2 min
- Flow rate How fast water leaves your kettle, measured in grams per second. Pour 150 g of water over 30 seconds and you poured at 5 g/s. It's the variable most home brewers never measure and most competition brewers rehearse. Intermediate 1 min
- Arabica Coffea arabica, the species behind essentially all specialty coffee. When a bag lists an origin, a farm, an altitude and a variety, it is talking about arabica — the species is so assumed that most specialty bags never bother to print it. Intro 1 min
- Robusta Coffea canephora, the other species people actually drink, and roughly 40 % of world production. It grows at low altitude, tolerates heat and disease that would kill arabica, yields more per tree, and costs far less. Vietnam is the largest producer on earth on the back of it. Intro 2 min