Must, n. [AS. must, fr. L. mustum (sc. vinum), from mustus young, new, fresh. Cf. Mustard.] 1. The expressed juice of the grape, or other fruit, before fermentation. “These men ben full of must.” Wyclif (Acts ii. 13.).
No fermenting must fills... the deep vats. Longfellow.
2. [Cf. Musty.] Mustiness.