necessary

American  

[nes-uh-ser-ee] / ˈnɛs əˌsɛr i /

adjective

1. essential, indispensable, or requisite.

   The rotor is a necessary part of the motor.

   Synonyms:

   needed

   Antonyms:

   dispensable

2. happening or existing by necessity.

   The snow has forced a necessary change in our plans.

3. acting or proceeding from compulsion or necessity; not free; involuntary.

   a necessary agent.

4. Logic.

   1. (of a proposition) such that a denial of it involves a self-contradiction.

   2. (of an inference or argument) such that its conclusion cannot be false if its supporting premises are true.

   3. (of a condition) such that it must exist if a given event is to occur or a given thing is to exist.

---

noun

necessaries plural

1. something necessary or required for a particular purpose; necessity.

   Synonyms:

   essential, requisite, requirement

2. Law. necessaries, food, clothing, etc., required by a dependent person and varying with their social or economic position or that of the person upon whom they are dependent.

3. Chiefly New England. a privy or toilet.

necessary British  

/ ˈnɛsɪsərɪ /

adjective

1. needed to achieve a certain desired effect or result; required

2. resulting from necessity; inevitable

   the necessary consequences of your action

3. logic

   1. (of a statement, formula, etc) true under all interpretations or in all possible circumstances

   2. (of a proposition) determined to be true by its meaning, so that its denial would be self-contradictory

   3. (of a property) essential, so that without it its subject would not be the entity it is

   4. (of an inference) always yielding a true conclusion when its premises are true; valid

   5. (of a condition) entailed by the truth of some statement or the obtaining of some state of affairs Compare sufficient

4. philosophy (in a nonlogical sense) expressing a law of nature, so that if it is in this sense necessary that all As are B, even although it is not contradictory to conceive of an A which is not B, we are licensed to infer that if something were an A it would have to be B

5. rare compelled, as by necessity or law; not free

---

noun

1. informal the money required for a particular purpose

2. informal to do something that is necessary in a particular situation

Synonym Usage

Necessary, essential, indispensable, requisite indicate something vital for the fulfillment of a need. Necessary applies to something without which a condition cannot be fulfilled or to an inevitable consequence of certain events, conditions, etc.: Food is necessary to life. Multiplicity is a necessary result of division. Indispensable applies to something that cannot be done without or removed from the rest of a unitary condition: Food is indispensable to living things. He made himself indispensable as a companion. Something that is essential forms a vitally necessary condition of something: Air is essential to red-blooded animals. It is essential to understand the matter clearly. Requisite applies to what is thought necessary to fill out, complete, or perfect something: She had all the requisite qualifications for a position.

Other Word Forms

Derived Forms

• necessariness
  noun
• quasi-necessary
  adjective

Inflected Forms

noun

• necessaries
  plural

Etymology

Origin of necessary

First recorded in 1300–50; Middle English necessarie, from Latin necessārius “unavoidable, inevitable, needful,” equivalent to necess(e) (neuter indeclinable adjective) “unavoidable, necessary” + -ārius -ary

Explanation

Everyone can agree that certain things are necessary for survival: food, water, shelter. Some people might add chocolate to that list. Necessary refers to anything you can't do without. Necessary, cede, and cease all come from the same root, cedere, which is Latin for "to go away" or "to give something up." When something's necessary, you won't give it up. That fudge-covered brownie sundae from your favorite ice-cream shop? It might seem like a decadent treat, but if you're a true chocolate lover you'll insist that it's as necessary as a warm jacket in winter.

Example Sentences

Social media is a necessary way to reach our generation, and it is a useful method to convey charm and personality, which help determine electability.

From The Wall Street Journal • Jun. 9, 2026

All of the experts I spoke with emphasized that responding well is necessary not just to save lives but also to contain the spread—a priority of governments the world over.

From Slate • Jun. 9, 2026

He argues this is necessary to tackle inequality and redistribute wealth from Peru's rich mineral, gold and copper reserves more equally and has enjoyed subsequent support in more rural areas.

From BBC • Jun. 8, 2026

“Part of what I want to convey here is that there’s not some ‘magic’ that’s necessary, that doesn’t exist for AI satellites,” Musk said in the video.

From MarketWatch • Jun. 8, 2026

The rope yanked me off the ground, and I screamed louder than necessary, to attract the trolls.

From "Rump: The (Fairly) True Story of Rumpelstilskin" by Liesl Shurtliff

Related Words

• basic
• crucial
• decisive
• essential
• fundamental
• imperative
• indispensable
• mandatory
• needed
• paramount
• required
• significant
• unavoidable
• urgent
• vital