Coffee glossary
Coffee brewing terms explained in plain English, from bloom to TDS.
What do coffee brewing terms mean?
Each entry defines one term in a sentence or two, then links to the brewing methods where it matters. Start with extraction, brew ratio and grind size: together they explain why coffee tastes sour, bitter or just right.
Acidity
Acidity in coffee is the bright, lively, juicy quality you taste on the tongue, like the tang of fruit.Agitation
Agitation is any movement of the coffee and water during brewing, such as stirring, swirling or a turbulent pour.Bloom
The bloom is the first small pour of water in a brew, usually 2–3 times the weight of the coffee, followed by a 30–45 second pause.Body
Body is how heavy and textured coffee feels in your mouth, from light and tea-like to thick and syrupy.Brew ratio
The brew ratio is the weight of coffee compared with the weight of water, written like 1:16 (1 g of coffee for every 16 g of water).Burr grinder
A burr grinder crushes coffee between two hard, ridged surfaces called burrs, set a fixed distance apart, so particles come out a consistent size.Bypass
Bypass is brew water that flows around the coffee bed instead of through it, for example down the sides of a filter, so it reaches the cup without extracting much flavour.Cafestol
Cafestol is a natural oil compound (a diterpene) found in coffee beans that can raise LDL cholesterol when consumed regularly in large amounts.Channelling
Channelling happens when water finds an easy path through the coffee bed instead of flowing evenly through all of it.Coffee concentrate
A coffee concentrate is coffee brewed much stronger than you would drink it, using less water, and then diluted with water, milk or ice to serve.Cold foam
Cold foam is milk frothed while it is still cold, then spooned on top of an iced coffee or cold brew.Crema
Crema is the golden-brown foam on top of an espresso.Crust
The crust is the layer of coffee grounds that floats on the surface during immersion brewing, held up by trapped gas.Decanting
Decanting means pouring brewed coffee off the grounds into a separate jug, flask or cup as soon as it is ready.Degassing
Degassing is the release of carbon dioxide from coffee beans after roasting.Dialling in
Dialling in means adjusting your recipe, usually the grind size first, until a coffee tastes right.Drawdown
Drawdown is the final stage of a pour-over brew, when you have stopped pouring and the remaining water drains through the coffee bed.Extraction
Extraction is the process of water dissolving flavour compounds out of ground coffee.Fines
Fines are the very small, dust-like particles that every grinder produces alongside the main grind.Flash brew
Flash brew is a way of making iced coffee by brewing hot coffee directly onto ice, so it cools instantly.Gasket
A gasket is the rubber or silicone ring that seals two parts of a coffee maker together, such as the top and bottom halves of a moka pot or the group head of an espresso machine.Grind size
Grind size is how finely coffee beans are broken up before brewing.Immersion vs percolation
Immersion brewing steeps all the coffee in all the water at once, as a French press does.Köpük
Köpük is the Turkish word for the thick foam on top of Turkish coffee.Metal filter
A metal filter is a fine stainless-steel mesh that holds back coffee grounds, as used in a French press plunger and some reusable pour-over filters.Microfoam
Microfoam is milk steamed so that the air in it forms very small, even bubbles, giving a silky, glossy texture rather than a stiff, bubbly froth.Nitro coffee
Nitro coffee is cold brew infused with nitrogen gas and poured from a tap, much like a stout beer.Portafilter
A portafilter is the handle-and-holder you fill with ground coffee and lock into an espresso machine.Pour-over
Pour-over is a way of making filter coffee by hand: you pour hot water over ground coffee in a filter cone and let it drip through into a cup or jug.Pulse pouring
Pulse pouring means adding the brew water in several smaller pours, letting the level drop a little between each, instead of one continuous pour.Roast level
Roast level describes how long and how hot coffee beans were roasted, usually labelled light, medium or dark.Robusta
Robusta is the common name for Coffea canephora, one of the two coffee species grown for most of the world's coffee; the other is arabica.Safety valve
A safety valve is a small pressure-release valve on the side of a moka pot base.Specialty coffee
Specialty coffee is high-quality coffee graded at 80 points or more out of 100 by trained tasters using the Specialty Coffee Association's scoring system.Steeping
Steeping is leaving ground coffee to sit in water so its flavour dissolves out, as in a French press or cold brew.Tamping
Tamping is pressing ground coffee down into a firm, flat, even layer with a tool called a tamper.Total dissolved solids (TDS)
Total dissolved solids (TDS) measures how much coffee is dissolved in the cup, shown as a percentage.Water hardness
Water hardness is the amount of dissolved minerals, mainly calcium and magnesium, in your water.