# must

/ˈməst/ (US) · /mˈʌst/ (UK)

Source: https://englishreference.com/word/must
Updated: 2026-08-01

## Senses

### 1. obligation or rule

modal verb · CEFR A1

you use this to say that something is necessary or is a rule.

For teachers: indicates a requirement, imperative, or strong obligation imposed by the speaker or an external authority.

- You must wear a seatbelt at all times while the car is moving.
- All employees must complete the safety training module before they are permitted to operate the heavy machinery on the factory floor.

Usage: followed by the bare infinitive without 'to'

### 2. logical certainty

modal verb · CEFR A2

you use this when you are almost certain that something is true based on the evidence.

For teachers: expresses a logical deduction or the speaker's certainty that a particular state of affairs exists.

- You have been working all day, so you must be very tired.
- Given the fingerprints found at the scene, the investigators concluded that the suspect must have entered through the unlocked side window.

Usage: often used with 'be' or 'have been'

### 3. a requirement

noun · CEFR B1

something that is necessary to have or do.

For teachers: something that is mandatory, essential, or highly recommended.

- If you visit Paris, seeing the Eiffel Tower is a must.
- For any serious scholar of ancient history, visiting the national archives is an absolute must during their research trip.

Usage: often used in the phrase 'a must' or 'a must-have'

### 4. grape juice

noun · CEFR C2 · Technical

the juice from crushed grapes before it becomes wine.

For teachers: the unfermented or fermenting juice expressed from fruit, especially grapes.

- The workers collected the fresh must in large wooden vats to begin the fermentation.
- The quality of the wine depends heavily on the sugar content and acidity of the must before the yeast is introduced.

Usage: uncountable in this sense

## Examples

- A warm coat is a must in this cold weather.
- If you visit the city, the local art museum is a must for any history lover.
- While the basic software package is functional, the security upgrade is an absolute must for any business handling sensitive client data in the current digital climate.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.