Espresso Glossary: 40 Coffee and Espresso Terms Explained

This guide is based on public information and manufacturer specifications. We do not claim hands-on testing. Prices and availability change often; check Amazon for current details.

Espresso has its own vocabulary. This glossary explains the terms you will meet in reviews and buying guides, in plain English.

Machine terms

Portafilter

The handle with a basket that holds the coffee and locks into the machine.

Basket

The metal filter that holds the grounds. Baskets come in single and double sizes.

Group head

The part of the machine the portafilter locks into, where hot water is delivered.

Shower screen

A perforated disc in the group head that spreads water across the coffee.

Boiler

A tank that heats water. Single boiler machines switch between brewing and steaming temperature.

Dual boiler

A machine with separate boilers for brewing and steaming so you can do both at once.

Thermoblock

A compact heating element that heats water quickly as it passes through. Common in entry-level machines.

Heat exchanger

A design that uses a steam boiler to heat brew water as it passes through a pipe.

PID

A controller that keeps water temperature steady by switching the heater on and off precisely.

Pump pressure (bar)

The force pushing water through the coffee. Many recipes use about 9 bar at the group head.

Pre-infusion

A gentle initial wetting of the coffee at low pressure before full pressure starts.

Steam wand

A tube that releases steam to heat and froth milk.

Three-way valve

A valve that releases pressure after the shot so the puck is drier and the machine can be backflushed.

Super-automatic

A machine that grinds, tamps, brews and often froths automatically.

Semi-automatic

A machine where you grind, dose and tamp, and the machine controls water and pressure.

Coffee and shot terms

Espresso

A concentrated coffee made by forcing hot water through finely ground coffee under pressure.

Crema

The golden foam on top of a fresh espresso shot.

Dose

The weight of ground coffee in the basket.

Yield

The weight of liquid espresso in the cup.

Brew ratio

Dose compared with yield, such as 1:2, meaning one part coffee to two parts espresso. See our brew ratio helper.

Extraction

How much of the coffee dissolves into the water. Under-extracted shots taste sour; over-extracted shots taste bitter.

Dialing in

Adjusting grind, dose and yield until a shot tastes balanced. See our grind size chart.

Channeling

When water finds an easy path through the puck, causing uneven extraction.

Tamping

Pressing the grounds flat and level in the basket.

Puck

The compressed disc of used grounds left in the basket.

Puck prep

Steps to level and prepare the grounds before tamping.

Shot time

How long the pump runs to produce the shot.

Ristretto

A shorter, more concentrated shot with less liquid.

Lungo

A longer shot made with more water.

Americano

Espresso diluted with hot water.

Latte and cappuccino

Espresso with steamed milk; a cappuccino has more foam and less milk than a latte.

Microfoam

Finely textured steamed milk with tiny bubbles.

Grinder terms

Burr grinder

A grinder that crushes beans between two burrs, giving a more even grind than a blade grinder.

Blade grinder

A grinder that chops beans with a spinning blade. Not suited to espresso.

Stepless

A grinder whose adjustment has no fixed steps, allowing very fine changes.

Retention

Grounds left inside the grinder after grinding.

Single dosing

Weighing in the amount of beans for each shot rather than filling a hopper.

Grind size

How coarse or fine the grounds are.

Upkeep terms

Descaling

Removing mineral buildup from the machine. See how to descale.

Backflushing

Cleaning the group head by pushing water backwards with a blind basket, on machines that allow it.

Purging

Releasing a little steam or water to clear the wand or group head.

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