modal verb

must

must, have to

You must finish your homework.

You must finish your homework.

It must be cold outside.

It must be cold outside.

You must not smoke in here.

You must not smoke in here.

must ((+ verb)) to express obligation or necessity You must finish your homework.

must ((+ verb)) to express a logical conclusion or certainty It must be cold outside.

must not ((+ verb)) to express prohibition You must not smoke in here.

Synonyms (obligation): have to, need to; (deduction): have to be. Antonyms: must not, needn't

From Old English 'moste', which was the past tense of 'motan' ('to be allowed, to have to').

'Must' is a very strong obligation. Think of it as a MASTER's command: "You MUST obey!"

This page is designed for learning support. Please use it as a learning reference, not as a formal reference.