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.

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noun

plural

necessaries

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

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noun

1. informal the money required for a particular purpose

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

Related Words

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

• necessariness noun
• quasi-necessary adjective

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

A claim is a necessary precursor to filing a lawsuit against a public agency.

From Los Angeles Times • Apr. 16, 2026

But in a world where war is possible, resilience is necessary.

From The Wall Street Journal • Apr. 15, 2026

While he was in hospital he was under 24-hour guard by prison officers but it was not deemed necessary to handcuff him.

From BBC • Apr. 15, 2026

In a memo to employees Wednesday, Snap Chief Executive Evan Spiegel said the cuts were necessary to enable the company to increase efficiency and pursue profitable growth.

From The Wall Street Journal • Apr. 15, 2026

This failure was expected to cause disruptions in air travel, banking, industry, electric grids, phone systems, and other critical services necessary for daily living at the turn of the century.

From "The First State of Being" by Erin Entrada Kelly

Related Words

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