Must: The unfermented juice of grapes extracted by crushing or pressing; grape juice in the cask or vat before it is converted into wine.
Must Weight: Measurement of the sugar content in grape must, or unfermented grape juice, which indicates the potential alcohol of the juice were all of the sugar to be converted to alcohol during fermentation. Like Brix, Baumé and Oechsle, must weight is more accurately a measurement of the must's density or specific gravity.
Musty: Having an off-putting moldy or mildewy smell. The result of a wine being made from moldy grapes, stored in improperly cleaned tanks and barrels, or contaminated by a poor cork.