Home coffee glossary: 35 terms from bar to thermoblock

How to use this glossary

The terms are in alphabetical order. Where a definition includes a figure, it comes either from our product database, in which case it is shown the same way as in our tables, or from a named source. Words in bold inside a definition have their own entry. If you are choosing a machine and want the reasoning as well as the vocabulary, start with bean-to-cup, pods or espresso machine.

A to B

AquaClean. Philips’s name for the water filter that sits in the tank of its bean-to-cup machines. Philips claims up to 5,000 cups without descaling if the filter is changed each time the machine asks, a figure based on eight filter changes (Philips Series 2200 Fully automatic espresso machines EP2220/14). See the water hardness guide.

Bar. A unit of pressure. On a spec sheet it is the pressure the pump is rated for: 15 bar on the Philips 2200, and the same on every machine in our UK tables that states one. It is not a useful way to tell models apart.

Basket. The perforated metal cup that sits in the portafilter and holds the ground coffee. Baskets come in one-cup and two-cup sizes, and as single wall or dual wall.

Bean hopper. The container on a bean-to-cup machine or grinder that holds whole beans before grinding. Philips states 275 g for the 2200.

Bean-to-cup machine. A machine that grinds whole beans, doses, brews and disposes of the grounds by itself, one cup at a time. Often called a fully automatic machine by manufacturers. See our bean-to-cup comparison.

Brew unit. The mechanism inside a bean-to-cup machine that receives the ground coffee, brews it and ejects the puck. Philips says brew group; De’Longhi says infuser or brewing unit. On many models it is removable for rinsing, which our tables record when the maker states it. See the cleaning guide.

Burr grinder. A grinder that crushes beans between two burrs, one fixed and one turning. The gap between them sets the grind size. Every grinder and built-in grinder in our database is of this kind.

C to D

Carafe. A milk container that attaches to a bean-to-cup machine and froths and dispenses milk automatically. De’Longhi’s version on the Magnifica Evo is called LatteCrema. See machines with a milk system.

Clark degree. The traditional English unit of water hardness, still used in some appliance manuals. To convert from mg/l as calcium carbonate, multiply by 0.07, the factor published by United Utilities (Water hardness). So 200 mg/l is 14 Clark degrees.

Conical and flat burrs. The two common burr shapes. In a conical set, a cone turns inside a ring; in a flat set, two discs face each other. Our tables give the shape when the maker states it. No manufacturer in our database publishes data that would rank one above the other.

Crema. The layer of fine, light-brown foam on top of an espresso. De’Longhi’s manuals use it as a sign when adjusting the grind: little crema and weak coffee point to a grind that is too coarse.

Descaling. Removing limescale from the water circuit with an acidic solution, in a programme the machine runs when it detects that one is due. See how to descale a bean-to-cup machine.

Dose. The weight of ground coffee used for one drink. Sage designs the Bambino’s baskets for 8 to 11 g (one cup) and 16 to 19 g (two cups) (the Bambino BES450/SES450 EN Quick Guide). The dose is the main driver of coffee cost per cup: see what a cup of coffee really costs.

Drip tray. The removable tray under the spouts that catches drips and rinse water. Many have a float that rises when the tray is full.

Dual wall basket. Sage’s term for a pressurised basket: a second wall with a small outlet regulates the pressure. Sage says to use it with pre-ground coffee and with older beans. The opposite of a single wall basket.

E to H

ESE pod. Easy Serving Espresso: a flat paper pod holding one pre-measured dose of ground coffee, for espresso machines with a suitable basket. Not to be confused with a pod in the capsule sense. Makers list the De’Longhi Dedica EC685 and Stilosa EC260 and the Krups Virtuoso as ESE compatible.

Espresso machine. On this site, a machine with a portafilter: you grind, dose and tamp, and the machine supplies hot water under pressure. Also called a manual or pump espresso machine. See our espresso machine comparison and the guide to a first espresso machine.

Extraction. What happens when hot water passes through ground coffee and dissolves part of it. Sage’s guide calls a shot over-extracted when the grind is too fine and the water barely passes, and under-extracted when the grind is too coarse and the water runs through too fast.

Grind setting. One position on a grinder’s adjustment scale. More settings mean smaller steps, not a better grind in itself. Stated numbers in our database run from 7 on the JURA E8 to 60 on the Sage Smart Grinder Pro. See the grind guide.

Grounds container. The box inside a bean-to-cup machine that collects used pucks. JURA states a capacity of 16 servings for the E8; most makers give no figure.

Group head. The part of an espresso machine that the portafilter locks into and through which hot water reaches the coffee.

Hardness. The amount of dissolved calcium and magnesium in water, usually given in mg/l as calcium carbonate. The Drinking Water Inspectorate describes water above 200 mg/l as hard and above 300 mg/l as very hard (Water Hardness / Hard Water). It determines how quickly limescale forms.

L to P

LatteGo. Philips’s milk system on some of its bean-to-cup machines: a two-part container with no tubes, according to Philips, which holds 0.26 l. See the Philips range guide.

Limescale. The chalky deposit left when hard water is heated. It builds up inside kettles and coffee machines and is the reason for descaling.

Milk hose. A milk system in which a flexible tube draws milk from a carton or separate container into the machine’s frother. The Siemens EQ.6 plus s300 and the JURA E8 work this way.

PID. An electronic controller that keeps the water temperature close to its target by constantly correcting the heating. Sage lists PID temperature control for the Bambino, the Bambino Plus and the Barista Express.

Pod. In the UK, usually a sealed aluminium or plastic capsule holding one dose of coffee for a specific brand’s machines. We do not list pod machines. Used pods can be recycled through Podback (Coffee pod recycling made easy).

Portafilter. The handle with a metal head that holds the basket and locks into the group head. Its diameter decides which baskets and tampers fit: Sage states 54 mm for the Bambino.

Pre-infusion. A short phase at the start of an espresso shot in which the coffee is wetted at low pressure before full pressure is applied. Sage describes it as gently expanding the grounds for a more even extraction.

Price bracket. Our rough guide to where a model sits. Each one is placed in one of four brackets, from entry level to premium. Where available, we also show the Amazon price, with the date and time we checked it: it is checked once a day and may have changed since, so the price that counts is the one Amazon shows when you buy.

S to W

Single wall basket. Sage’s term for a non-pressurised basket. Sage says to use it with freshly ground beans, because it lets grind, dose and tamping shape the result. It demands a capable grinder: see the grinder comparison.

Steam wand. A metal tube that releases steam for heating and frothing milk in a jug. Bean-to-cup makers often call theirs a milk frother or cappuccino maker. On some espresso machines the wand froths automatically.

Tamping. Pressing the ground coffee flat and firm in the basket before brewing. Sage’s guide suggests about 15 to 20 kg of pressure and adds that pressing the same way every time matters more than the exact force.

Thermoblock. A heating system that heats water as it flows through, with no stored boiler of hot water. Several makers in our database state it. Sage calls its own fast-heating system ThermoJet and states a heat-up time of 3 s for the Bambino.

Water filter. A cartridge placed in the water tank to reduce scale. Each maker states its own replacement interval: about two months for De’Longhi’s, three months or 40 litres for Sage’s on the Bambino. See AquaClean.

Terms we avoid, and why

You will not find scores, stars or “winners” defined here, because we do not award any. Our comparisons rest on manufacturer data, and our own measurements will only come once we own the machines: the method page explains what is planned. Nor do we define noise ratings, since no manufacturer in our database publishes one.

Where to go next

• To work out your running costs: the cost per cup calculator.
• To avoid the classic traps: eight common buying mistakes.
• To narrow down a model: the machine finder below.