Word family noun necessity the necessaries the necessary adjective necessary ≠ unnecessary verb necessitate adverb necessarily ≠ unnecessarily
From Longman Dictionary of Contemporary Englishnecessaryne‧ces‧sa‧ry1 /ˈnesəsəri $ -seri/ ●●● S2 W1 adjective 1 NEEDsomething that is necessary is what you need to have or need to do → essential The booklet provides all the necessary information about the college. No further changes were considered necessary.absolutely/really necessary The police are advising motorists to travel only if their journey is absolutely necessary.it is necessary (for somebody) to do something It’s not necessary to wear a tie. The doctor says it may be necessary for me to have an operation.make it necessary (for somebody) to do something Falling profits made it necessary to restructure the business.necessary for (doing) something A good diet is necessary for maintaining a healthy body.if/when/where necessary I’ll stay up all night, if necessary, to get it finished.RegisterIn everyday English, instead of saying it is necessary for somebody to do something, people usually say that someone has to do something: The doctor says it might be necessary for me to have an operation. → The doctor says I might have to have an operation.2 → necessary connection/consequence etc3 → a necessary evilTHESAURUSnecessary used to describe something that you need to have or doMake sure you bring the necessary documents with you.It may be necessary for you to have a small operation.essential very important and necessary, especially in order to be healthy, successful etcVitamins are essential for healthy growth.The tourist industry is an essential part of the Spanish economy.vital extremely important and necessary, especially in order to avoid serious problemsA vital piece of equipment on the spacecraft had stopped operating.It is vital that the aid is sent immediately.compulsory if something is compulsory, you must do it because of a rule or lawMaths and Science are compulsory subjects.All new staff undergo a compulsory training course.obligatory if something is obligatory, you must do it because of a rule or law. Obligatory is more formal than compulsoryThe use of seatbelts is obligatory.Safety regulations have made it obligatory for all competitors to wear fist protectors.mandatory if something is mandatory, you must do it because it is the law. Mandatory is more formal than compulsory and sounds strongerSchool attendance is mandatory.a prisoner serving a mandatory life sentencerequisite /ˈrekwəzət/ formal [usually before noun] the requisite things are the ones that you need to have in order to do somethingThe other candidates lacked the requisite skills.the requisite evidence needed for a successful prosecution Examples from the Corpus
necessary• She explained why change was necessary.• Add a second layer if necessary.• Jennie told Katharine to be aware of this and to correct any fault as necessary.• Computers are as necessary as textbooks in schools.• They also make any necessary criticisms and suggestions more easily acceptable when they are offered.• He produced the necessary documents and handed them to her.• Fats in our diet are necessary for both heat and energy.• The doctor says it may be necessary for me to have an operation.• This was clearly necessary for their analysis since it allowed them to aggregate data over different drivers.• Much doubling, therefore, is necessary in the tutti.• It will be necessary to close the pool while the repairs take place.• On his eighteenth birthday, his parents had believed it necessary to commit the act that would decisively save their only child.• But take another step back and it is no longer necessary to preserve the species.• If necessary, we will have to employ some outside people to finish the job.absolutely/really necessary• The approach to the tournament should be as low key as possible with changes being made only where absolutely necessary.• Use faxes and phones-only when absolutely necessary.• This is not absolutely necessary but it would stretch your imagination and further clarify the entire research process from beginning to end.• In truth, a guide wasn't really necessary for our party that good-weather day.• On the other hand, honesty is an absolutely necessary policy as a matter of principle and also credibility.• All of the changes have been absolutely necessary to keep Sparta alive.• It is not really necessary to locate the degree of premeditated dishonesty involved in the politics of policy formulation.necessarynecessary2 noun 1 → necessaries2 → do the necessaryOrigin necessary (1300-1400) Latin necessarius, from necesse “necessary”, from ne- “not” + cedere “to give up” 