noun
necessity
nuh-SESS-uh-tee/nəˈsesəti/
The condition of being required or unavoidable.
The necessity of food and water guides the traveler's packing.

Etymology
“Not” plus “withdraw” gives the original image of “no backing away.” A necessity is something from which there is no evasion: circumstances make it required, rather than optional.
In context
… quiet by necessity to quiet by choice.
More examples
- We question the necessity of another meeting.
- She works two jobs out of necessity.
- The shelter provides basic necessities like food and clothing.
Forms
necessity · necessities
necessary adjective — Needed or required in a situation.
necessarily adverb — As an unavoidable result or consequence.
Similar words
- need
- Need emphasizes a requirement, without always implying something unavoidable.
- requirement
- Requirement often refers to a condition imposed by rules.
- inevitability
- Inevitability stresses that something cannot be prevented or avoided.