• (stressed) IPA: /ˈmʌst/
• (unstressed) IPA: /məs(t)/

From Middle English moste "must", literally, "had to", the past tense of Middle English moten, from Old English mōste, 1st & 3rd person singular past tense of mōtan ("to be allowed, be able to, have the opportunity to, be compelled to, must, may"), from Proto-Germanic *mōtaną.

must (must, no present participle; simple past must, no past participle)

1. (modal auxiliary, defective) To 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.

   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Acts 9:6 ↗:

     Arise, and go into the city, and it shall be told thee what thou must do.

2. (modal auxiliary, defective) To 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.

   You picked one of two, and it wasn't the first: it must have been the second.

3. (modal auxiliary, defective) Used to indicate that something is very likely, probable, or certain to be true.

   The children must be asleep by now.

• French: devoir
• German: müssen
• Italian: dovere
• Portuguese: dever
• Russian: (predicative) до́лжен
• Spanish: deber, tener que

• French: devoir
• Italian: dovere
• Portuguese: dever
• Russian: должно́ быть
• Spanish: deber de

must (plural musts)

1. Something that is mandatory or required.

   Synonyms: imperative, necessity

   Antonyms: no-no

   Hyponyms: must-do, must-have, must-see

   If you're trekking all day, a map is a must.

• French: must, obligation
• German: Muss
• Italian: obbligo, dovere
• Portuguese: dever

From Middle English must, from Old English must and Old French must, most, both from Latin mustum.

must

1. The property of being stale or musty.
2. Something that exhibits the property of being stale or musty.
3. Fruit juice that will ferment or has fermented, usually from grapes.

• French: moût or mout
• German: Most
• Italian: mosto
• Portuguese: mosto
• Russian: муст
• Spanish: mosto

must (musts, present participle musting; simple past and past participle musted)

1. (transitive) To make musty.
2. (intransitive) To become musty.

From Persian مست, from Pahlavi 𐭬𐭮𐭲.

must

1. Alternative form of musth
   • 1936, George Orwell, Shooting an Elephant, an essay in the magazine New Writing:

     It was not, of course, a wild elephant, but a tame one which had gone ‘must’.