Exact historical dictionary sense
Must in Webster's 1913 dictionary
The 1913 record labels must as noun. Its source-bounded etymology and selected historical definition appear below.
[AS. must, fr. L. mustum (sc. vinum), from mustus young, new, fresh. Cf. Mustard.]
Cross-verified historical senseIn Webster's Revised Unabridged Dictionary (1913), "must" is labeled noun. Its etymology is recorded as: "[AS. must, fr. L. mustum (sc. vinum), from mustus young, new, fresh. Cf. Mustard.]" The selected historical definition says: "The expressed juice of the grape, or other fruit, before fermentation."