Meaning & use
Mustn't
Last updated
Contraction of 'must not,' used to say that something is prohibited or strongly inadvisable.
See it in a sentence
You mustn't forget to lock the door before you leave.
Children are taught early on that they mustn't talk to strangers.
A note on using this word
An informal contraction common in speech and casual writing; the apostrophe replaces the missing 'o' in 'not.'
Words with a similar meaning
must not
Choose a synonym to suit the sentence. Meanings can overlap without being identical.
Words with an opposite meaning
must
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