must

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To be obliged or required by morality, law, or custom.
• intransitive verb To be compelled, as by a physical necessity or requirement.
• intransitive verb Used to express a command or admonition.
• intransitive verb To be determined to; have as a fixed resolve.
• intransitive verb Used to indicate inevitability or certainty.
• intransitive verb Used to indicate logical probability or presumptive certainty.
• intransitive verb To be required or obliged to go.
• noun Something that is absolutely required or indispensable.
• noun Musk.
• noun The unfermented or fermenting juice expressed from fruit, especially grapes.
• noun The quality or condition of being stale or musty.

from The Century Dictionary.

• 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.
• To grow stale and moldy; contract a sour or musty smell.
• To make stale and moldy; make musty or sour.
• noun New wine; the unfermented juice as pressed from the grape.
• noun . The stage or condition of newness: said of wine.
• noun The pulp of potatoes prepared for fermentation.
• noun Mold or moldiness; fustiness.
• Frenzied; in the state of madness known as must: as, a must elephant.
• noun A condition of strong nervous excitement or frenzy to which elephants are subject, the paroxysms being marked by dangerous irascibility.

from the GNU version of the Collaborative International Dictionary of English.

• noun The expressed juice of the grape, or other fruit, before fermentation.
• noun Mustiness.
• To be obliged; to be necessitated; -- expressing either physical or moral necessity
• To be morally required; to be necessary or essential to a certain quality, character, end, or result
• verb To make musty; to become musty.
• adjective (Zoöl.) 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A time during which male elephants exhibit increased levels of sexual activity and aggressiveness (also musth)
• verb modal auxiliary, defective to do with certainty; indicates that the speaker is certain that the subject will have executed the predicate
• verb modal auxiliary, defective 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
• noun Something that is mandatory or required
• noun Something that exhibits the property of being stale or musty
• noun Fruit juice that will ferment or has fermented, usually grapes
• verb transitive To make musty.
• verb intransitive To become musty.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun grape juice before or during fermentation
• adjective highly recommended
• noun the quality of smelling or tasting old or stale or mouldy
• noun a necessary or essential thing