Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “must”

See all translations

must

modal verb uk   strong /mʌst/ weak /məst/ /məs/ us  

must modal verb (NECESSARY)

A2 used to show that it is necessary or very important that something happens in the present or future: Meat must be cooked thoroughly. I must get some sleep. You mustn't show this letter to anyone else. Luggage must not be left unattended (= it is against the rules). formal Must you leave so soon? formal "Must I sign this?" "Yes, you must." If you say that you must do something, you mean that you strongly intend to do something in the future: I must phone my sister. We must get someone to fix that wheel. I mustn't bite my nails. used for emphasis: I must say, you're looking extremely well. I must admit, I wasn't looking forward to it.B1 If you tell someone else that they must do something pleasant, you are emphasizing that you think it is a good idea to do that: You must come and stay with us for the weekend. We must meet for lunch soon.
More examples

must modal verb (PROBABLY)

B2 used to show that something is very likely, probable, or certain to be true: Harry's been driving all day - he must be tired. There's no food left - we must have eaten it all. When you got lost in the forest you must have been very frightened. "You must know Frank." "No, I don't."
More examples

must

noun [C] uk   strong /mʌst/ weak /məst/ /məs/ informal us  
something that is necessary: If you live in the country a car is a must.
(Definition of must modal verb, noun from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of must?
Add Cambridge dictionaries to your browser to your website

Definitions of “must” in other dictionaries

Word of the Day

ellipsis

a situation in which words are left out of a sentence but the sentence can still be understood

Word of the Day

Euphemisms (Words used to Avoid Offending People)

by Kate Woodford,
March 04, 2015
​​​ We recently looked at the language that we use to describe lies and lying. One area of lying that we considered was ‘being slightly dishonest, or not speaking the complete truth’. One reason for not speaking the complete truth is to avoid saying something that might upset or offend people. Words and

Read More 

snapchat verb

March 02, 2015
to send someone a message using the photomessaging application Snapchat We used to have a thing until he got a girlfriend. now

Read More