Definitions
1.VerbTo do as a requirement; indicates that the sentence subject is required as an imperative or directive to execute the sentence predicate, with failure to do so resulting in a failure or negative consequence."You must arrive in class on time.; This door handle must be rotated fully.; Everybody told me I must stop worrying, but I couldn't, because I felt there must be something wrong.; You really must come and see us soon, pal. - We'll see: I can borrow my dad's car, but I must bring it back before midnight.; The physician said that I must / had to / would have to stop smoking."
2.VerbTo do with certainty; indicates that the speaker is certain that the subject will have executed the predicate."If it has rained all day, it must be very wet outside.; Where would you have put the keyring? You couldn’t have lost it again! - I must have, because it's nowhere to be found.; I said it must be pretty late and I really must go.; She's being taken to the police car now , so they must be going to arrest her."
3.VerbUsed to indicate that something is very likely, probable, or certain to be true."The children must be asleep by now.; There's the doorbell. It must be Dad."
4.NounSomething that is mandatory, required or recommended."If you're trekking all day, a map is a must."
5.NounThe property of being stale or musty.
6.NounSomething that exhibits the property of being stale or musty.
7.NounFruit juice that will ferment or has fermented, usually from grapes.
8.VerbTo make musty.
9.VerbTo become musty.
10.NounAlternative spelling of musth.