Over-Extraction
过萃
GrindingDefinition
The state in which too much soluble material has been pulled from the grounds, especially the late-arriving bitter and astringent compounds. Typical causes are grinding too fine, brewing too long, water that is too hot, or too much agitation. In the cup it reads as dry, harsh, ashy bitterness that coats the tongue and outlasts the finish.
Etymology
The prefix over-, meaning excess, attached to extraction - a natural coinage once brewers needed one word for the bitter end of the flavor range.
In use
The verdict on a shot that tastes harsh and chalky - 'it's over-extracted, back off the grind' is standard barista shorthand.