Tra từ necessity - Từ điển Oxford Advanced Learner 8th

ne·ces·sity [necessity necessities] BrE [nəˈsesəti] NAmE [nəˈsesəti] noun
1. uncountable the fact that sth must happen or be done; the need for sth
•~ (for sth) We recognize the necessity for a written agreement.
•~ (of sth/of doing sth) We were discussing the necessity of employing more staff.
•~ (for sb) to do sth There had never been any necessity for her to go out to work.
•There is absolutely no necessity for you to be involved.
•This is, of necessity, a brief and incomplete account.
2. countable a thing that you must have and cannot manage without
•Many people cannot even afford basic necessities such as food and clothing.
•Air-conditioning is an absolute necessity in this climate.
3. countable, usually singular a situation that must happen and that cannot be avoided
•Living in London, he felt, was an unfortunate necessity.
more at make a virtue of necessity at ↑virtue
Idiom: ↑necessity is the mother of invention

Word Origin:
late Middle English: from Old French necessite, from Latin necessitas, from necesse ‘be needful’.

Example Bank:
•Culling of the animals was born out of the necessity for successful conservation.
•Driven by financial necessity, she decided to give up her writing career.
•Food is a necessity of life.
•He argued that nuclear weapons were a political necessity.
•He is changing job out of necessity, not because he particularly wants to.
•I've never felt the necessity to rely on such a strict rule.
•Most disputes can be resolved without the necessity of going to court.
•Most of the women are forced, through economic necessity, to work in part-time low-paid jobs.
•Mrs R has been spared the necessity of having to give evidence.
•Necessity forced an urgent solution.
•Observers stressed the necessity for the ceasefire to be observed.
•Policies which address these issues are an urgent necessity.
•She saw the necessity to make an immediate impression on him.
•Sleep is an absolute necessity for life.
•The company sees no necessity for a more cautious approach to investment.
•The people in the rural areas use mud bricks only as an immediate, practical necessity.
•The visit will, of necessity, be brief.
•There's no necessity for you to come.
•These animals don't like water but will swim if the necessity arises.
•They have accepted the necessity of greater state intervention.
•They have nothing but the barest necessities.
•This rule is carried no farther than necessity requires.
•Where necessity demands, we can seat more guests in the gallery.
•You can dial direct without the necessity of going through the operator.
•the necessity to earn a living
•Living in London he felt, was an unfortunate necessity.