endless

Compared meaning: lasting for a long time (adjective).

比较义项：持续时间长的（形容词）。

• long

  Long is the neutral, general word for extended duration (or distance); it carries no strong emotional tone and combines freely with nouns like 'long time', 'long wait', 'long friendship'.

  long 是表示“持续时间长”（或“距离长”）的中性、基础说法，没有强烈的情感色彩，可自由搭配 a long time、a long wait、a long friendship 等。

  They have been close friends for a long time.

  他们已经做了很长时间的好朋友了。

• lifelong

  Lifelong specifically means lasting for someone's entire life; it is used as an attributive adjective before nouns like friend, dream, or ambition, not to describe generic duration.

  lifelong 特指“持续一生”的时长，通常作定语放在名词前（如 friend、dream、ambition），而不是用来泛泛描述持续时间。

  She has had a lifelong passion for painting since childhood.

  她从小就对绘画有终身的热爱。

• endless 本词

  Endless suggests a duration that feels subjectively too long or tedious, as if it will never stop; it often carries a mildly negative or exaggerated tone, unlike neutral long.

  endless 强调一种主观上“感觉长得没有尽头”的时长，常带有轻微的负面或夸张语气，令人厌烦，不同于中性的 long。

  The meeting felt endless, and everyone wanted to go home.

  这次会议感觉没完没了，大家都想回家了。

Long, lifelong, and endless all mean lasting a long time. Long is the neutral, general word. Lifelong means lasting a whole life, used before words like friend or dream. Endless suggests something feels too long, almost never stopping. Not covered: long meaning far in distance.

这三个词都能表示“持续时间长”，但侧重点不同：long 是最基础、中性的说法，可指时间也可指距离；lifelong 强调贯穿一生，常作定语修饰人际关系或目标；endless 带有主观夸张色彩，强调“看不到尽头”，多用于令人厌烦、难以忍受的等待。这里不比较 long 表示“（距离）长的”这一义项。

Compared meaning: lasting for a long time (adjective).

比较义项：持续时间很长的（形容词）。

• lengthy

  Formal word implying something is tediously or excessively long; typically describes meetings, speeches, explanations, or documents.

  较正式的词，暗示某事冗长乏味，多用于会议，演讲，解释或文件。

  The professor gave a lengthy explanation before finally answering the question.

  教授先给出了一段冗长的解释，然后才终于回答了问题。

• long

  The everyday, neutral word for a long duration; combines freely with almost any noun and fits the common phrase 'for a long time'.

  最普通中性的说法，几乎可以搭配任何名词，也常用于“for a long time”这样的短语。

  We've known each other for a long time, since primary school.

  我们从小学起就认识了，已经很长时间了。

• lifelong

  Means lasting for someone's entire life; used only for things tied to a whole lifetime, such as friendships, dreams, or early habits.

  指贯穿一个人的一生，只用于伴随终生的事物，如友谊，梦想或从小养成的习惯。

  They became lifelong friends after meeting in college.

  他们在大学相识后，成为了终身好友。

• endless 本词

  Emphasizes that something feels like it has no end, often used with exaggeration to express boredom, frustration, or impatience.

  强调某事仿佛没有尽头，常带夸张语气，表达厌烦，沮丧或不耐烦的情绪。

  Waiting in that line felt endless, so we finally decided to leave.

  排那个队感觉没完没了，我们最后决定离开了。

Lengthy, long, lifelong, and endless all mean lasting a long time. Lengthy means tediously long, like a speech. Long is neutral. Lifelong means lasting a whole life, for friendships or dreams. Endless feels like it never ends. Not covered: long can mean far away.

这四个词都可以表示“持续时间很长”，但语气和用法不同：lengthy强调冗长，常显得乏味，多用于正式场合；long是最普通中性的说法；lifelong特指贯穿一生，只能用于友谊，梦想等伴随终生的事物；endless则带夸张语气，强调“感觉没有尽头”，常表达不耐烦。这里不比较long表示“距离长”的义项（如a long road）。