let

Compared meaning: to let someone do something (verb).

比较义项：允许某人做某事，或允许某事发生（动词）。

• let 本词

  Informal and conversational; followed directly by a bare infinitive (let sb do sth, never to do), and often describes tolerating or allowing something to happen rather than formally approving it.

  非正式、口语化；后面直接接不带 to 的动词原形（let sb do sth，而非 to do），且常表示听任某事发生，而不是正式批准。

  My parents let me stay out late last night.

  昨晚我父母让我在外面待到很晚。

• allow

  Neutral in register, common in both speech and writing; uses the pattern allow sb to do sth, and is the usual choice for rules or permissions set by a person in authority.

  语气中性，口语和书面语都常用；句型为 allow sb to do sth（宾语后接 to 不定式），是描述权威人物或规则所给许可时最常用的词。

  The teacher didn't allow phones during the final exam.

  老师在期末考试期间不允许使用手机。

• permit

  Formal, often official or legal in tone, typical of written rules and regulations; also uses permit sb to do sth, but sounds stiff or overly formal in casual personal situations.

  语气正式，常带有官方或法律色彩，多见于书面规则和法规；句型也是 permit sb to do sth，但用在日常私人场合会显得生硬、过于正式。

  The city council will not permit new construction near the river.

  市议会不会准许在河边附近新建建筑。

Let, allow, and permit all mean to give permission, but formality differs. Let is informal, followed by the base verb, as in let someone go. Allow is neutral, common in speech and writing. Permit is formal, for written rules. Not compared: permit as a document.

这三个词在“允许”这个意义上很接近，但正式程度不同：let 最口语化，allow 中性通用，permit 最正式，常见于官方或书面语境。这里不比较 permit 作名词时的“许可证”义，也不比较 let 的“出租（房屋）”等其他义项。

Compared meaning: to rent out property to someone (verb).

比较义项：出租（房产）（动词）。

• let 本词

  Informal, mainly British English word for renting out property to someone; carries no sense of a formal written contract and is often used for short-term lets like a room or a flat.

  非正式说法，主要用于英式英语，指把房产出租给别人，不强调正式的书面合同，常用于房间、公寓等短期出租。

  They let the flat above the shop to a young couple.

  他们把店铺楼上的公寓出租给了一对年轻夫妇。

• lease

  Formal, legal term implying a signed contract for a fixed period; common in both British and American English, often for longer-term or commercial property.

  正式的法律用语，指通过签订合同、约定固定期限来出租房产，英式和美式英语都常用，多用于较长期或商业性质的房产。

  The landlord leased the office space to a startup for five years.

  房东将这间办公空间出租给了一家初创公司，租期五年。

Let and lease both mean to rent property to someone. Let is informal and mainly British, used for short lets like a room. Lease is formal and legal, meaning a signed contract, often for longer periods. Let's other meaning, 'to allow', is not compared here.

在这个意义上，let 和 lease 都表示把房产出租给别人，但 let 语气随意、常用于英式口语，而 lease 强调签订正式的租赁合同，语气更正式、法律色彩更浓。这里不比较 let 的“允许，准许”义，也不比较 lease 表示“承租，从别人那里租用”的用法。