to be obliged; to be necessitated; -- expressing either physical or moral necessity; as, a man must eat for nourishment; we must submit to the laws.-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.-the expressed juice of the grape, or other fruit, before fermentation.-mustiness.-to make musty; to become musty.