Definition

1. Modal Verb:

   • To be obliged or required to: Expresses necessity, obligation, or compulsion, often from external rules, laws, or strong personal conviction.
   • To be very likely or certain to: Expresses a logical deduction or a high degree of certainty about a situation.

2. Noun:

   • An essential or necessary item: Something that is absolutely required or highly recommended.
   • The juice of grapes or other fruit before or during fermentation.
   • Mold or staleness; mustiness (archaic).

3. Adjective:

   • Essential, mandatory, or highly recommended: Describes something that is absolutely necessary or imperative to experience or have.

Usage Examples

• Modal Verb (Necessity):
  • You must wear a seatbelt while driving. (It is a legal requirement.)
  • I must finish this report by tomorrow. (It is an obligation from my job.)
• Modal Verb (Logical Certainty):
  • She isn't answering her phone. She must be in a meeting. (This is a logical conclusion.)
  • You've been traveling all day. You must be tired. (This expresses a high probability.)
• Noun (Essential Thing):
  • A good pair of hiking boots is a must for this trip.
  • This new novel is a must for fans of the genre.
• Adjective:
  • This documentary is must-see television.
  • He is a must-have player for any championship team.

Advanced Usage

• "Must not" vs. "Don't have to": "Must not" expresses prohibition ("You must not smoke here."). "Don't have to" expresses a lack of necessity ("You don't have to come if you're busy.").
• Past Deduction with "must have": Used to express certainty about a past event.
  • The ground is wet. It must have rained last night.
• Emphatic Suggestion: Used to give strong, enthusiastic advice.
  • You must visit the new art exhibition; it's fantastic!

Variants and Related Words

• Musty (adj): Having a stale, moldy, or damp smell.
  • The old books in the attic had a musty odor.
• Musth (n): A periodic state of heightened aggression and sexual activity in male elephants.
  • The bull elephant was in musth.

Synonyms

• Modal Verb (Necessity): Have to, need to, ought to, should.
• Noun (Essential): Necessity, essential, requirement, prerequisite.
• Adjective: Essential, indispensable, mandatory, required.

Related Phrases

• A must-do: An activity that is highly recommended.
  • Seeing the sunrise from the mountain peak is a must-do.
• If you must: A reluctant concession, often implying disapproval.
  • "Can I borrow your pen?" "Well, if you must."

Related Idioms

• Needs must (when the devil drives): A saying meaning that sometimes you are forced to do something out of necessity.
  • I don't like working weekends, but needs must if we want to finish the project.

Adjective

1. highly recommended
   • a book that is must reading

Noun

1. the quality of smelling or tasting old or stale or mouldy
2. grape juice before or during fermentation
3. a necessary or essential thing
   • seat belts are an absolute must