must Definition

must¹
auxiliary verb

1. Used to express necessity

Example: I must earn some extra money
Example: Must you leave so soon?
2. Used to express duty or obligation.

Example: You must help him
3. Used to express certainty.

Example: You must be Charles
4. Used to express determination.

Example: I must remember to go to the bank
5. Used to express probability.

Example: She must be there by now
6. Used to express inevitability.

Example: We must all die some time
7. Used to express an invitation or suggestion. Also used with the main verb merely implied. See also mustn't.

Example: You must come and see us soon
Example: You must read her other books
Example: I must away

noun

1. A necessity; something essential.

Example: Fitness is a must in professional sport
Thesaurus: necessity, essential, need, requirement, prerequisite, sine qua non, imperative, obligation, duty, stipulation, provision.
Form: a must (always)

Idiom: must needs

See needs must at need.

Etymology: Anglo-Saxon moste, originally as past tense of mot may.

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must²
noun

1. The juice of grapes or other fruit before it is completely fermented to become wine.

Etymology: Anglo-Saxon: from Latin mustum vinum new wine.

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must³
noun

1. Mustiness; mould.

Etymology: 17c.

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must⁴ musth

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musth
must
noun

1. A dangerous frenzied state in certain male animals, especially bull elephants in the breeding season.

Form: to be in musth (especially in)

Etymology: 19c: from Persian and Hindi mast intoxicated.