must

1 of 4

verb

məs(t), 

ˈməst 

present tense and past tense, all persons must

auxiliary verb

1

a

: be commanded or requested to

You must stop.

b

: be urged to : ought by all means to

You must read that book.

2

: be compelled by physical necessity to

One must eat to live.

: be required by immediate or future need or purpose to

We must hurry to catch the bus.

3

a

: be obliged to : be compelled by social considerations to

I must say you're looking well.

b

: be required by law, custom, or moral conscience (see conscience sense 1) to

We must obey the rules.

c

: be determined to

If you must go at least wait for me.

d

: be unreasonably or perversely compelled to

Why must you argue?

4

: be logically inferred (see infer sense 1) or supposed to

It must be time.

5

: be compelled by fate or by natural law to

What must be will be.

6

: was or were presumably certain to : was or were bound to

If he did it she must have known.

7

dialect : may, shall

—used chiefly in questions

intransitive verb

archaic : to be obliged to go

… I must to Coventry.

—William Shakespeare

must

2 of 4

noun (1)

ˈməst 

1

: an imperative need or duty : requirement

Finishing by tomorrow is a must.

2

: an indispensable item : essential

Exercise is a must.

must

3 of 4

noun (2)

: the expressed juice of fruit and especially grapes before and during fermentation

also : the pulp and skins of the crushed grapes

must

4 of 4

noun (3)

1

: musk

2

: mold entry 3, mustiness

Synonyms of must

Verb

• should
• shall

Noun (1)

• requirement
• necessity
• need
• necessary

Examples of must in a Sentence

Verb

we must be quiet during the performance

Noun (1)

exercise is a must if you want to stay healthy

Recent Examples on the Web

Noun

For decades, a summer trip to Europe has been considered a must for travelers in the know. —Julia Buckley, CNN Money, 15 Nov. 2025

Lastly, a sturdy mount is a must for successful observing. —Anthony Wood, Space.com, 15 Nov. 2025

Mashed potatoes are a must, of course—Garten’s Make-Ahead Goat Cheese Mashed Potatoes recipe is perfect for preparing ahead of time. —Sophia Beams, Better Homes & Gardens, 15 Nov. 2025

Having previously worked for a top celebrity florist in LA, flowers were a must for Nussdorf—and the in-house florist not only makes arrangements to decorate the space each day, but will also whizz them up for customers who want to purchase their own. —Florence O'Connor, Vogue, 14 Nov. 2025

Word History

Etymology

Verb and Noun (1)

Middle English moste, from Old English mōste, past indicative & subjunctive of mōtan to be allowed to, have to; akin to Old High German muozan to be allowed to, have to

Noun (2)

Middle English, from Old English, from Latin mustum

Noun (3)

Middle English (Scots) moist, from Middle French must, alteration of musc musk

First Known Use

Verb

before the 12th century, in the meaning defined at sense 1a

Noun (1)

1598, in the meaning defined at sense 1

Noun (2)

before the 12th century, in the meaning defined above

Noun (3)

15th century, in the meaning defined at sense 1

Phrases Containing must

• if someone must
• if you must know
• I must love you and leave you
• must-have
• must not
• must-see
• the show must go on
• you/he/she must be joking

Rhymes for must

• bused
• bust
• crust
• cussed
• dust
• fussed
• fust
• gust
• just
• lust
• mussed
• rust

Kids Definition

must

1 of 2 helping verb

məs(t) 

ˈməst

present & past all persons must

1

: is commanded, requested, or urged to

the train must stop

you must read that book

2

: is forced, required, or obliged to

leaves must fall

one must eat to live

we must be quiet

3

: is determined to

if you must go

4

: is very likely to

it must be time

must have lost it

5

: is certain to

the bus must be coming

must

2 of 2 noun

ˈməst 

: something required or absolutely necessary

new shoes are a must

Medical Definition

must

noun

ˈməst 

: the expressed juice of fruit and especially grapes before and during fermentation