What does "must" mean?

Must: To be morally required; to be necessary or essential to a certain quality, character, end, or result; as, he must reconsider the matter; he must have been insane. Likewise must the deacons be grave. 1 Tim. iii.

Additional senses

  1. 2.Morover, he [a bishop] must have a good report of them which are without. 1 Tim. iii.
  2. 3.Note: The principal verb, if easy supplied by the mind, was formerly often omitted when must was used; as, I must away. "I must to Coventry." Shak.
  3. 4.The expressed juice of the grape, or other fruit, before fermentation. "These men ben full of must." Wyclif (Acts ii.
  4. 5.). No fermenting must fills ... the deep vats. Longfellow.
  5. 6.Etym: [Cf. Musty.] Mustiness.
  6. 7.To make musty; to become musty.

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