necessary

[nes-uh-ser-ee]

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

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

/ 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

Other Word Forms

• necessariness noun
• quasi-necessary adjective

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

Word History and Origins

Origin of necessary¹

C14: from Latin necessārius indispensable, from necesse unavoidable

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.

Example Sentences

Rabbit, 48, said he hadn’t heard of the president’s plan to send in the National Guard, but didn’t think it was necessary.

From Los Angeles Times

“I think this is a very necessary fight.”

From Los Angeles Times

"We will always take all actions necessary at the domestic level to keep UK citizens safe."

From BBC

The administration frames these actions as necessary steps to protect American communities and enforce existing immigration law.

From Los Angeles Times

Sable continues to contend it has followed all necessary protocols and met all legal requirements.

From Los Angeles Times

Related Words

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