necessary
Americanadjective
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essential, indispensable, or requisite.
The rotor is a necessary part of the motor.
- Synonyms:
- needed
- Antonyms:
- dispensable
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happening or existing by necessity.
The snow has forced a necessary change in our plans.
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acting or proceeding from compulsion or necessity; not free; involuntary.
a necessary agent.
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Logic.
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(of a proposition) such that a denial of it involves a self-contradiction.
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(of an inference or argument) such that its conclusion cannot be false if its supporting premises are true.
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(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
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something necessary or required for a particular purpose; necessity.
- Synonyms:
- essential, requisite, requirement
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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.
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Chiefly New England. a privy or toilet.
adjective
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needed to achieve a certain desired effect or result; required
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resulting from necessity; inevitable
the necessary consequences of your action
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logic
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(of a statement, formula, etc) true under all interpretations or in all possible circumstances
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(of a proposition) determined to be true by its meaning, so that its denial would be self-contradictory
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(of a property) essential, so that without it its subject would not be the entity it is
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(of an inference) always yielding a true conclusion when its premises are true; valid
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(of a condition) entailed by the truth of some statement or the obtaining of some state of affairs Compare sufficient
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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
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rare compelled, as by necessity or law; not free
noun
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informal the money required for a particular purpose
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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
Inflected Forms
Nouns
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.
Vocabulary lists containing necessary
Commonly Misspelled Words, List 1
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Very Necessary: Synonyms for "Important"
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Workshop 3, Part 1
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
EU officials rejected that argument, saying the measures are necessary to prevent dominant platforms from disadvantaging rivals.
From BBC ● Jul. 23, 2026
UniCredit expects to dictate the German bank’s strategy from the beginning of next year, and that it would be in a position to call a shareholder vote to exercise its control if necessary, Orcel said.
From The Wall Street Journal ● Jul. 23, 2026
And one in five Americans believes Social Security is all that’s necessary, even though it replaces only 40% of the average worker’s wages when retiring at age 65.
From MarketWatch ● Jul. 23, 2026
But Yampolskiy and Russell both agree that it’s not inevitable or necessary that we rush full steam ahead with little regulation and too few safeguards.
From Los Angeles Times ● Jul. 23, 2026
Hunter’s position is that the funding is necessary but I won’t give them access to my research.
From "Boy 2.0" by Tracey Baptiste
Latinos are necessaries for the North American community.
From Los Angeles Times ● Mar. 12, 2025
Meanwhile, lingering inflation has still been high enough to hold back spending by consumers who had to set more money aside for necessaries like food and utility bills.
From Washington Times ● Oct. 31, 2023
I’ve promised myself “Little Dorrit” this year and some other unopened necessaries.
From New York Times ● Oct. 1, 2020
“In the last years of her life, before Congress purchased her husband’s papers, she was in a state of absolute poverty, and I think sometimes suffered for the necessaries of life,” Jennings wrote.
From Washington Post ● Jun. 7, 2018
The process was slow and difficult, the necessaries costly and hard to acquire.
From "A Clash of Kings" by George R.R. Martin
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.