Coffee Brewing Terms, Explained: A Plain-Language Glossary

Good coffee has a vocabulary, and most of it points at one idea: getting water to pull flavor out of the grounds evenly. Here are the terms worth knowing, grouped by where they come up.

Extraction and strength

• Extraction — water dissolving flavor out of the grounds. Too little tastes sour and thin; too much tastes bitter; balanced is the goal. The master concept behind everything else. See why grind size changes extraction.
• Under-extraction — not enough flavor pulled out: sour, salty, weak. Usually too coarse a grind, too short a brew, or water too cool.
• Over-extraction — too much pulled out: bitter, harsh, drying. Usually too fine a grind, too long a brew, or water too hot.
• Strength — how concentrated the cup is (how much dissolved coffee per unit of water). Set mostly by the coffee-to-water ratio. Not the same as extraction: a cup can be strong and under-extracted.
• TDS (total dissolved solids) — the percentage of the brew that’s dissolved coffee, a precise measure of strength. Balanced brewed coffee is roughly 1.15–1.45%.

Grind

• Particle distribution — the spread of grind sizes in a batch. A tight, uniform distribution extracts evenly; a wide one tastes muddy. This is the whole case for a burr grinder over a blade.
• Fines — the smallest particles, coffee dust. A few are normal; too many over-extract (bitterness) and clog filters.
• Boulders — oversized chunks. Water can’t reach their centers, so they under-extract and add sourness.
• Grind retention — coffee left stuck inside the grinder after grinding. High retention means stale grounds mixing into your next fresh dose.
• Burr alignment — how parallel and true a grinder’s two burrs sit. Good alignment gives a tighter particle distribution; poor alignment widens it.

Brewing

• Bloom — the foaming when hot water first hits fresh grounds, as roasting CO₂ escapes. A short “bloom pour” and pause lets the gas out so the main pour saturates evenly. Central to pour-over.
• Degassing — fresh-roasted beans releasing CO₂ over days after roasting. Very fresh coffee can brew unevenly because the gas pushes water away; a few days’ rest helps.
• Agitation / turbulence — stirring or pouring force that moves the grounds around, which speeds and evens extraction. Too much can over-extract; too little leaves dry pockets.
• Channeling — water rushing through one path in the coffee bed instead of soaking it evenly, so part over-extracts and part under-extracts. Fought with an even grind and even wetting.
• Drawdown — the time it takes the last water to drain through a pour-over bed. A very slow drawdown often means too fine a grind or clogging fines; very fast means too coarse.
• Immersion vs. percolation — the two ways to brew. Immersion steeps grounds in a body of water (French press, cold brew); percolation flows water through a bed (pour-over, drip).

Espresso terms (in brief)

• Dose / yield / ratio — the grams of grounds in (dose), grams of liquid out (yield), and their ratio (commonly around 1:2). How espresso is portioned, instead of by the pot.
• Pre-infusion — a gentle wetting of the puck before full pressure, which reduces channeling.
• Crema — the reddish-brown foam on a fresh espresso shot, from emulsified oils and CO₂.

Why the vocabulary is worth it

None of these terms are decoration — each one names a lever you can actually pull. Knowing that “muddy” coffee is really fines over-extracting from a wide particle distribution tells you the fix (a better, more even grind), where “my coffee tastes bad” doesn’t. Start with the two that move the cup most: grind size and the coffee-to-water ratio. If grind consistency is the lever you want to improve, our best burr coffee grinders guide is the place to start.