View synonyms for necessary


[ nes-uh-ser-ee ]


  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. Compare sufficient ( def 2 ).


, plural nec·es·sar·ies.
  1. something necessary or required for a particular purpose; necessity.

    Synonyms: essential, requisite, requirement

  2. necessaries, Law. 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.


/ ˈnɛsɪsərɪ /


  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
“Collins English Dictionary — Complete & Unabridged” 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012


  1. the necessary informal.
    the money required for a particular purpose
  2. do the necessary informal.
    to do something that is necessary in a particular situation
“Collins English Dictionary — Complete & Unabridged” 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Other Words From

  • neces·sari·ness noun
  • quasi-neces·sary adjective
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Word History and Origins

Origin of necessary1

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
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Word History and Origins

Origin of necessary1

C14: from Latin necessārius indispensable, from necesse unavoidable
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Synonym Study

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.
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Example Sentences

Center Nicklas Backstrom said the Capitals have grown passive when playing with a lead when aggressiveness is necessary.

“Federal funding — together with the region’s commitment — will support the major maintenance and capital rehabilitation activities that are necessary to restore and improve the aging transit system,” the letter said.

The audit also found that the agency does not keep track of who owes money or how much they owe, and it isn’t taking necessary steps to collect it.

While 84 percent of registered Republicans supported the recall, increased support among Democrats and independents will be necessary for Newsom to lose.

They’ve noted, too, that they would pursue a vote to bar him from federal office if he was convicted by the necessary 67 members of the Senate.

From Vox

He could order the Justice Department to begin the necessary regulatory work.

Yet, what my peers do not realize – or cannot handle – is that rejection is a necessary part of forging a romantic relationships.

But as is her way, Kaling defended why the episode was not only funny, but necessary.

Unfortunately, the underground tunnels that were used to transport booze and, if necessary, escaping patrons, are off-limits.

However, we have just had a necessary wake-up call that all is not as secure as we believed.

In sorting notes it is necessary to be able readily to distinguish between notes of this bank and notes of other reserve banks.

As long as may be necessary, Sam,” replied Mr. Pickwick, “you have my full permission to remain.

But it was necessary to take Silan, which the rebels hastened to strengthen, closely followed up by the Spaniards.

For this use of the voice in the special service of will-power, or propelling force, it is necessary first to test its freedom.

It is only necessary to have a zinc, or a galvanized tray on which to stand the glass in an inverted position.





necessarilynecessary condition