English definition of “must”
strong /mʌst/ weak /məst/, /məs/ modal verb
NECESSARY › used to say that it is necessary that something happens or is done: The meat must be cooked thoroughly. You mustn't show this letter to anyone else. I must get some sleep.
LIKELY › used to show that you think something is very likely or certain to be true: It must have been very upsetting for her. You must be exhausted. She must be very wealthy.
SUGGEST › used to show that you think it is a good idea for someone to do something: You must come and stay with us some time.