necessity

Compared meaning: something needed or required (noun).

比较义项：必需的事物、必需品（名词）。

• necessity 本词

  The most common, everyday word for something people cannot do without; often used in the phrase 'a basic necessity' and applies to both physical items and abstract needs.

  最常见、最口语化的词，用来指人们不可缺少的东西；常用于“a basic necessity”（基本必需品）这一说法，既可指具体物品，也可指抽象需求。

  For many rural families, a reliable car is a necessity, not a luxury.

  对许多农村家庭来说，一辆可靠的汽车是必需品，而不是奢侈品。

• essential

  Usually used in the plural 'the essentials' for the basic items or steps needed for a particular task or situation; more casual and concrete than necessity or requisite.

  通常以复数形式“the essentials”出现，指完成某件事或应对某种情况所需的基本物品或基本要素；比 necessity 和 requisite 更随意、更具体。

  Pack the essentials — a map, water, and a flashlight — before you go hiking.

  去徒步之前，先把必需品——地图、水和手电筒——打包好。

• requisite

  Formal and somewhat old-fashioned; used with 'for' or 'of' to name something officially or formally required, typical of legal, academic or bureaucratic contexts.

  语气正式、略显书面化；常与 for 或 of 搭配，用来指官方或正式要求具备的东西，多见于法律、学术或行政等正式场合。

  Fluency in French is a requisite for this diplomatic position.

  流利的法语是担任这个外交职位的必需条件。

Necessity, essential and requisite all mean something needed. Necessity is the most common word for something people cannot do without. Essential is usually used as essentials, the basic items needed for a task. Requisite is formal, used with for or of in official contexts.

necessity、essential 和 requisite 在表示“必需的事物”时意思相近，但语气和正式程度不同：necessity 最常用、最口语化；essential 常以复数形式 essentials 表示某件事或某种情况所需的基本物品；requisite 则更正式、书面化，常与 for/of 搭配，用于申请、法律等正式场合。这里不比较 necessity 表示“必要性”的抽象义项（如 out of necessity），也不比较 essential 和 requisite 常见的形容词用法（如 essential skills、the requisite documents）。