length

Compared meaning: how long something lasts in time (noun).

比较义项：某事物持续的时间（时长）（名词）。

• length 本词

  The common, everyday word for how long something lasts; it can also mean physical size, so listeners rely on context to know it refers to time, not size.

  这是表示持续时间的常见口语词；它也可以表示物体的物理长度，因此听者需要依靠语境来判断它指的是时间而非长度。

  This movie's length is over three hours, so bring some snacks for later.

  这部电影时长超过三小时，记得带点零食。

• duration

  A more formal word used only for time, common in official, scientific or written contexts such as flights, treatments and contracts; it sounds stiff in casual conversation.

  这是一个更正式的词，只用来表示时间，常见于航班、疗程、合同等官方、科技或书面语境；在日常口语中使用会显得生硬。

  Please note that no refunds are issued regardless of the duration of your subscription.

  请注意，无论订阅时长多长，恕不退款。

Length and duration both mean how long something lasts, but length is the common, everyday word; it can also mean physical size, so context shows whether it means time. Duration is formal and used only for time, common in official writing like flights or contracts.

这两个词都表示某事物持续多长时间，但语域不同：length更口语化、更常见，也可以指物体的物理长度，需要靠语境判断是否表示时间；duration更正式，多用于官方、科技或书面语境（如航班、疗程、合同），专指时间，不会引起歧义。这里不比较length表示物理长度的义项。