Definition

1. Adjective:

   • Required to be done, achieved, or present; needed; essential: Something that is "necessary" must happen or exist because it is required by circumstances, logic, or natural law.
   • Inevitably resulting from or logically following from conditions: A "necessary" outcome or conclusion is one that is certain and unavoidable given the preceding facts or premises.

2. Noun:

   • A thing that is needed or essential: "Necessaries" (often used in plural) are items or conditions required for a particular purpose or for basic living.
   • (The necessary) Informal: A term for money needed for a purpose, or (dated British informal) a toilet.

Usage Examples

• Adjective:

  • A passport is necessary for international travel.
  • It is necessary to drink water to survive.
  • Given the evidence, a guilty verdict was a necessary conclusion.

• Noun:

  • The government provided food and other necessaries to the refugees.
  • I've packed all the necessaries for the camping trip.
  • (Informal) He went to the bank to get the necessary for the car payment.

Advanced Usage

• Philosophical/Logical Necessity: In logic and philosophy, a "necessary" condition is one without which something cannot occur or be true. Its counterpart is a "sufficient" condition.

  • Oxygen is a necessary condition for combustion, but it is not sufficient on its own (you also need fuel and heat).

• Necessary Evil: A common idiom describing something undesirable that must be accepted or endured to achieve a beneficial result.

  • Paying taxes is often seen as a necessary evil.

Variants and Related Words

• Necessitate (verb): To make something necessary as a result or requirement.
  • The storm necessitated a change of plans.
• Necessity (noun): The state or fact of being required or unavoidable; an indispensable thing.
  • Water is a basic necessity of life.
• Necessarily (adverb): As a necessary result; inevitably.
  • Expensive food is not necessarily better.

Synonyms

• Adjective: Essential, required, needed, indispensable, vital, mandatory, obligatory, inevitable, unavoidable.
• Noun: Requirement, essential, requisite, prerequisite, need.

Antonyms

• Adjective: Unnecessary, superfluous, optional, dispensable, nonessential, avoidable.
• Noun: Luxury, extra, nonessential.

Related Phrases and Idioms

• If necessary: Used to indicate what will be done if it becomes required.
  • We can postpone the meeting if necessary.
• A necessary part of: An essential component.
  • Trust is a necessary part of any strong relationship.
• Do the necessary: (Informal) To do what is required in a situation.
  • I'll do the necessary to get the project back on track.

Adjective

1. unavoidably determined by prior circumstances
   • the necessary consequences of one's actions
2. absolutely essential

Noun

1. anything indispensable
   • food and shelter are necessities of life
   • the essentials of the good life
   • allow farmers to buy their requirements under favorable conditions
   • a place where the requisites of water fuel and fodder can be obtained