must

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To be obliged or required by morality, law, or custom: Citizens must register in order to vote.
2. v. To be compelled, as by a physical necessity or requirement: Plants must have oxygen in order to live.
3. v. Used to express a command or admonition: You must not go there alone. You simply must be careful.
4. v. To be determined to; have as a fixed resolve: If you must leave, do it quietly.
5. v. Used to indicate inevitability or certainty: We all must die.
6. v. Used to indicate logical probability or presumptive certainty: If the lights were on, they must have been at home.
7. v. Archaic To be required or obliged to go: "I must from hence” ( Shakespeare).
8. n. Something that is absolutely required or indispensable: Promptness on the job is a must. Comfortable boots are a must when going on a hike.
9. n. The quality or condition of being stale or musty.
10. n. The unfermented or fermenting juice expressed from fruit, especially grapes.
11. n. Variant of musth.
12. n. Musk.

Century Dictionary and Cyclopedia

1. To be obliged; be necessarily compelled; be bound or required by physical or moral necessity, or by express command or prohibition, or by the imperative requirements of safety or interest; be necessary or inevitable as a condition or conclusion: as, a man must eat to live; we must obey the laws; you must not delay. Like other auxiliaries, must was formerly used without a following verb (go, get, and the like): as, we must to horse.
2. n. New wine; the unfermented juice as pressed from the grape.
3. n. . The stage or condition of newness: said of wine.
4. n. The pulp of potatoes prepared for fermentation.
5. n. A condition of strong nervous excitement or frenzy to which elephants are subject, the paroxysms being marked by dangerous irascibility.
6. To grow stale and moldy; contract a sour or musty smell.
7. To make stale and moldy; make musty or sour.
8. n. Mold or moldiness; fustiness.
9. Frenzied; in the state of madness known as must: as, a must elephant.

Wiktionary

1. v. to do with certainty; indicates that the speaker is certain that the subject will have executed the predicate
2. v. to do as a requirement; indicates that the sentence subject is required as an imperative or directive to execute the sentence predicate, with failure to do so resulting in a negative consequence
3. n. Something that is mandatory or required
4. n. Something that exhibits the property of being stale or musty
5. n. Fruit juice that will ferment or has fermented, usually grapes
6. n. A time during which male elephants exhibit increased levels of sexual activity and aggressiveness (also musth)

GNU Webster's 1913

1. To be obliged; to be necessitated; -- expressing either physical or moral necessity
2. To be morally required; to be necessary or essential to a certain quality, character, end, or result
3. n. The expressed juice of the grape, or other fruit, before fermentation.
4. n. Mustiness.
5. v. To make musty; to become musty.
6. adj. Being in a condition of dangerous frenzy, usually connected with sexual excitement; -- said of adult male elephants which become so at irregular intervals, typicaly due to increased testosterone levels.

WordNet 3.0

1. n. grape juice before or during fermentation
2. adj. highly recommended
3. n. the quality of smelling or tasting old or stale or mouldy
4. n. a necessary or essential thing