important

Compared meaning: main or most important (adjective).

比较义项：主要的，最重要的（形容词）。

• principal

  Principal is used before nouns to name the chief one among several within an institution or hierarchy (principal shareholder, principal office); it has a formal, almost official tone.

  principal 常放在名词前，用来指出机构或等级中最主要的那一个（如 principal shareholder「主要股东」、principal office「总部」），语气正式、带有官方色彩。

  The principal shareholder of the company owns forty percent of its shares.

  这家公司的主要股东持有百分之四十的股份。

• primary

  Primary highlights the one that comes first in rank or order among several goals, sources, or concerns, and is the standard word in phrases like primary goal, primary source, and primary concern.

  primary 强调在多个目标、来源或考虑因素中排在首位，是 primary goal（首要目标）、primary source（主要来源）、primary concern（首要关切）等固定搭配的常用词。

  The senator's primary goal this year is to lower taxes for working families.

  这位参议员今年的首要目标是为工薪家庭减税。

• important 本词

  Important is the everyday, general word for having great value or effect; it works freely as a standalone claim (it is important that...) without ranking one thing above others.

  important 是日常最通用的词，表示具有重大价值或影响，可以独立作出判断（如 it is important that……），不必暗示要在几者中排出主次。

  It is important to drink plenty of water every single day.

  每天喝足够的水是很重要的。

• fundamental

  Fundamental describes something forming the essential base that everything else depends on, closer to 'foundational' than merely 'important', and pairs with principle, right, or part.

  fundamental 表示构成事物赖以存在的基础部分，含义更接近「基础性的」而不仅仅是「重要的」，常与 principle、right、part 等词搭配。

  Trust is a fundamental part of any strong friendship.

  信任是任何牢固友谊中不可或缺的基础部分。

Principal, primary, important, and fundamental all mean main or most important, but differ in strength and formality. Principal names the chief one in a group. Primary marks what comes first. Important is the general word. Fundamental means the essential base.

这些词在「主要的、最重要的」这一意义上相近，但语气强弱、正式程度和搭配习惯不同。这里不比较 principal 作名词表示「校长」的用法，也不比较 primary 表示「最初级的」（如 primary school「小学」）的用法。

Compared meaning: having power or influence over others (adjective).

比较义项：对他人或局势有权势、影响力（形容词）。

• important 本词

  Describes someone or something highly regarded or central in status, without necessarily implying real power, expertise, or control over others — milder than the rest.

  形容某人或某事物地位很高、备受重视，但不一定意味着真正拥有权力、专业能力或对他人的控制——语气比其余几个词更温和。

  Grandma was the most important person in our family, though she never sought power.

  奶奶是我们家里最重要的人，尽管她从未追求过权力。

• powerful

  Emphasizes real strength or control that lets someone dominate situations or people, often through force, wealth, or position, regardless of whether others admire or trust them.

  强调真正的力量或控制力，使某人能够支配局势或他人，往往依靠武力、财富或地位，而不论他人是否敬佩或信任他们。

  The powerful drug lord controlled the entire city's underground economy.

  那个强大的毒枭掌控着整座城市的地下经济。

• influential

  Focuses on shaping other people's opinions, choices, or behavior over time, usually through ideas, reputation, or example rather than direct force.

  侧重于长期影响他人的观点、选择或行为，通常是通过思想、声望或榜样，而非直接的强制力。

  Her blog became so influential that celebrities started following her advice.

  她的博客变得非常有影响力，以至于名人们都开始听从她的建议。

• authoritative

  Describes a confident, expert manner or an official right to command that makes people trust, obey, or feel reassured; about credibility and legitimacy, not raw power.

  形容一种自信、专业的态度，或拥有正式的指挥权，使人信服、服从或感到安心；强调的是可信度和合法性，而不是纯粹的力量。

  The doctor sounded so authoritative that the nervous patient immediately calmed down.

  医生的语气非常权威，让紧张的病人立刻平静了下来。

Important, powerful, influential, and authoritative can all mean having power or influence, but the focus differs. Important means highly regarded, without real power. Powerful means real strength or control. Influential means shaping opinions over time, not by force. Authoritative means an expert, official manner.

这些词都可以形容某人或某事物对他人或局势具有权势或影响力，但侧重点和语气不同：important 侧重地位重要、受人重视；powerful 侧重实际的控制力和力量；influential 侧重对思想、决定或事件的影响；authoritative 侧重拥有正式权威或说话态度令人信服。这里不比较 important 表示「必要的、重要的」（如喝水很重要）等泛指重要性的用法。