From Arabica to WDT tools, this glossary covers 90 essential coffee terms every home barista should know. Whether you are dialing in your first espresso or exploring single-origin beans, each entry explains what the term means and why it matters to your cup.
A
Acidity
A desirable quality in coffee describing bright, lively, tangy sensations — not sourness or stomach acid.
AeroPress
A compact, portable brewer that uses air pressure to push water through coffee for a smooth, fast cup.
Aftertaste
The flavor that lingers on the palate after swallowing — a key indicator of coffee quality and complexity.
Altitude
The elevation at which coffee is grown — one of the strongest predictors of bean density, acidity, and flavor complexity.
Anaerobic Fermentation
A controlled processing technique where coffee ferments in oxygen-free tanks, producing intense and unusual flavors.
Arabica
The most widely consumed coffee species, prized for its complex flavors and smooth acidity.
B
Backflushing
A cleaning process for espresso machines that forces water and detergent backward through the group head to remove coffee oil buildup.
Batch Brewer
A high-end commercial drip machine designed for cafés that brews large volumes of pour-over-quality coffee automatically.
Bitterness
A taste sensation in coffee that ranges from pleasant dark chocolate depth to harsh, unpalatable over-extraction.
Blade Grinder
A grinder that chops beans with a spinning blade, producing uneven particle sizes and inconsistent extraction.
Blend
A coffee composed of beans from two or more origins, combined to achieve a balanced and consistent flavor profile.
Body
The physical weight, texture, and mouthfeel of coffee — how heavy or light it feels on your palate.
Bottomless Portafilter
A portafilter with the bottom removed, exposing the filter basket for direct observation of espresso extraction.
Brew Pressure
The force applied to push water through the espresso puck, standardized at approximately 9 bars for traditional espresso.
Brew Ratio
The relationship between the weight of dry coffee in and liquid espresso out, expressed as a ratio like 1:2.
Brew Temperature
The temperature of water used for brewing — one of the most influential variables in coffee extraction.
Burr Alignment
The precision with which a grinder's burr surfaces are parallel to each other — critical for even grinding performance.
Burr Grinder
A coffee grinder that crushes beans between two abrasive surfaces (burrs) for consistent, uniform particle size.
Bypass
Adding clean water to brewed coffee to adjust strength while preserving the extraction level.
C
Caramelization
The thermal breakdown of sugars during roasting that produces sweetness, color, and caramel-like flavors.
Channeling
When water finds paths of least resistance through the coffee puck, causing uneven extraction and flavor imbalance.
Chemex
An hourglass-shaped pour-over brewer known for its thick paper filters and exceptionally clean, bright cups.
Coffee Cherry
The fruit of the coffee plant — a small, round berry containing the seeds we know as coffee beans.
Cold Brew
Coffee brewed by steeping coarse grounds in cold or room-temperature water for 12 to 24 hours.
Conical Burr
A cone-shaped inner burr nested inside a ring burr, producing a bimodal grind distribution at lower speeds.
Cupping
The standardized tasting protocol used by coffee professionals to evaluate aroma, flavor, and quality.
D
Dark Roast
Coffee roasted at or past second crack, producing bold, smoky, low-acid flavors with visible surface oil.
Degassing
The release of carbon dioxide from freshly roasted coffee beans over the days following roasting.
Descaling
The process of removing mineral buildup (limescale) from coffee equipment to maintain performance and taste.
Development Time
The period from first crack to the end of a roast, where flavor complexity develops.
Distribution Tool
A leveling device spun across the portafilter to evenly distribute ground coffee before tamping.
Dose
The weight of dry ground coffee loaded into the portafilter basket before tamping, typically 18–20 grams for a double.
Drip Coffee
An automatic brewing method where a machine heats water and drips it over a bed of ground coffee into a carafe.
E
Espresso
A concentrated coffee brewed by forcing hot water through finely ground coffee under high pressure.
Extraction Percentage
The percentage of soluble material dissolved from coffee grounds during brewing — the key to balanced flavor.
Extraction Time
The total time water is in contact with the coffee puck during an espresso shot, typically 25 to 30 seconds.
F
First Crack
An audible popping sound during roasting that signals the beans have reached light roast territory.
Flat Burr
Two parallel disc-shaped burrs that produce a unimodal grind distribution prized for clarity and flavor separation.
Flavor Wheel
A visual reference tool mapping coffee flavors from broad categories to specific descriptors, used worldwide for cupping.
French Press
An immersion brewer that steeps coarse grounds in hot water before pressing them out with a metal mesh plunger.
G
Green Bean
The processed, unroasted seed of the coffee cherry — the raw material that roasters transform into roasted coffee.
Green Coffee
Raw, unroasted coffee beans as they arrive from origin before any heat is applied.
Grind Calibration
Adjusting a grinder's zero point and setting range to ensure accurate, repeatable grind sizes across the adjustment dial.
Grind Setting
The adjustable control on a grinder that determines the gap between burrs and therefore the output particle size.
Grind Size
The coarseness or fineness of ground coffee particles, which directly controls extraction rate and brew flavor.
Group Head
The component on an espresso machine where the portafilter locks in and water is delivered to the coffee puck at pressure.
H
Honey Process
A hybrid processing method where some fruit mucilage is left on the bean during drying, creating sweet, complex cups.
K
Kalita Wave
A flat-bottom pour-over dripper with wave-shaped filters and three small drain holes for consistent, forgiving brews.
L
Light Roast
Coffee roasted to just after first crack, preserving bright acidity and origin character.
M
Maillard Reaction
A chemical browning reaction between amino acids and sugars that creates coffee's complex flavors and aromas.
Medium Roast
Coffee roasted to a balanced point between first and second crack, offering a mix of origin character and roast sweetness.
Microns
A unit of measurement (one-thousandth of a millimeter) used to describe coffee grind particle size with precision.
Moka Pot
A stovetop brewer that uses steam pressure to push water up through fine grounds, producing strong, espresso-style coffee.
Mouthfeel
The tactile texture of coffee on the palate — beyond weight, encompassing smoothness, astringency, and creaminess.
N
Natural Process
A coffee processing method where cherries are dried whole with the fruit intact, producing fruity, full-bodied cups.
O
Over-Extraction
When too many soluble compounds are pulled from coffee grounds, producing bitter, harsh, astringent flavors.
P
Parchment
The thin, papery protective shell surrounding the green coffee bean inside the cherry.
Percolator
A brewer that cycles boiling water repeatedly through a basket of grounds, producing strong, bold coffee.
PID Controller
An electronic temperature controller that maintains precise, stable brew water temperature on espresso machines.
Portafilter
The handled device that holds the filter basket of ground coffee and locks into an espresso machine's group head.
Pour-Over
A manual brewing method where hot water is poured over ground coffee in a filter.
Pre-Infusion
A low-pressure wetting phase before full-pressure extraction that saturates the coffee puck for more even espresso.
Puck Screen
A thin metal mesh disc placed on top of the coffee puck to improve water distribution and keep the group head clean.
Q
Q Grader
A certified coffee professional trained and tested to evaluate coffee quality using SCA cupping standards.
R
Retention
The amount of ground coffee that remains trapped inside a grinder after grinding, which goes stale and contaminates future doses.
Roast Date
The date coffee was roasted — the most reliable indicator of freshness on a bag of whole-bean coffee.
Roast Profile
The planned time-temperature curve that guides a coffee roast from start to finish.
Robusta
A hardy coffee species with higher caffeine, stronger body, and a bold, bitter flavor profile.
RPM
Revolutions per minute — the rotational speed of grinder burrs, affecting heat, noise, static, and grind quality.
S
SCA Score
A 100-point quality rating system developed by the Specialty Coffee Association for evaluating coffee through standardized cupping.
Seasoning
Running initial coffee through new grinder burrs to stabilize grind performance and remove manufacturing residues.
Second Crack
A quieter, more rapid crackling sound during roasting that indicates the beans are entering dark roast territory.
Single Origin
Coffee sourced from one specific country, region, farm, or lot rather than blended from multiple sources.
Single-Dose Grinding
Weighing a precise dose of beans and grinding them all at once, with no beans left in the hopper between sessions.
Siphon Brewer
A vacuum coffee brewer that uses vapor pressure and gravity to produce a clean, aromatic cup through a theatrical process.
Specialty Coffee
Coffee scoring 80+ on the SCA scale, produced with attention to quality at every stage from farm to cup.
Sweetness
A fundamental positive quality in coffee where natural sugars and caramelization produce pleasant sweet flavors without added sugar.
T
Tamper
A tool used to compress ground coffee into a level, even puck inside the portafilter before espresso extraction.
Tasting Notes
Descriptive flavor references printed on coffee bags — like 'citrus, chocolate, caramel' — that describe a coffee's flavor profile.
TDS
Total Dissolved Solids — a measurement of how much coffee material is dissolved in your brewed cup.
Terroir
The combination of soil, climate, altitude, and environment that gives coffee from a specific place its unique character.
Third Wave Water
A mineral supplement added to distilled water to create optimized brewing water with ideal mineral composition.
Turkish Coffee
An ancient brewing method that simmers ultra-fine coffee powder in water in a small pot called a cezve, served unfiltered.
U
Under-Extraction
When not enough soluble compounds are pulled from coffee grounds, producing sour, thin, undeveloped flavors.
V
V60
A cone-shaped pour-over dripper from Hario with spiral ribs and a large drain hole for fast, precise brewing.
Vietnamese Phin
A small metal gravity dripper used to brew strong, concentrated Vietnamese-style coffee, often served with condensed milk.
W
Washed Process
A coffee processing method where fruit is removed before drying, producing clean, bright, transparent cups.
Water Hardness
The mineral content of water — primarily calcium and magnesium — that significantly affects coffee flavor and extraction.
WDT Tool
The Weiss Distribution Technique — using thin needles to break up clumps and distribute grounds evenly in the portafilter.
Y
Yield
The weight of liquid espresso extracted into the cup, typically 36–40 grams for a standard double shot.