unwritten

Compared meaning: spoken, not written down (adjective).

比较义项：口头的，非书面的（形容词）。

• oral

  Oral emphasizes the physical act of speaking itself, common in formal, academic or legal contexts (an oral exam, oral history, an oral agreement), contrasting precisely and formally with written.

  oral 强调“说话”这一行为本身，常见于正式、学术或法律语境（如 oral exam 口试、oral history 口述历史、oral agreement 口头协议），与 written（书面的）形成较为正式、精确的对照。

  Every student must take an oral exam at the end of the course.

  每个学生在课程结束时都必须参加一次口试。

• verbal

  Verbal is the everyday word for spoken as opposed to written, especially with agreement, warning or abuse; strictly it means 'in words' and can technically cover writing too.

  verbal 是日常生活中表示“口头的（相对于书面的）”最常用的词，尤见于 agreement、warning、abuse 等搭配；严格来说它本义是“用言语表达的”，理论上也可以包括书面形式。

  He gave a verbal warning instead of writing anything down.

  他只给了口头警告，没有写下任何书面记录。

• unwritten 本词

  Unwritten describes rules, laws, agreements or traditions that exist only by custom and were never formally recorded — broader than 'spoken', since they may never be said aloud at all.

  unwritten 用于描述仅凭习惯存在、从未被正式记录下来的规则、法律、协议或传统，含义比“口头的”更宽，因为这些规则可能根本没有被人说出口。

  There is an unwritten rule that you arrive early for meetings.

  有一条不成文的规定，就是开会要早到。

Oral, verbal, and unwritten all mean spoken, not written. Oral stresses the act of speaking, common in formal or legal contexts. Verbal is the everyday word for spoken versus written, though it can technically include writing. Unwritten describes rules or traditions never formally recorded.

这三个词在“口头、非书面的”这一意义上很接近，容易混淆，但语域和搭配不同：oral 强调“说”这一行为本身，多用于正式、学术或法律语境；verbal 是日常最常用的“口头的（相对于书面的）”一词，严格来说本义是“用言语表达的”，理论上也可包括书面形式；unwritten 则指规则、法律、传统等从未被正式记录下来，含义比“口头的”更宽，未必曾被说出口。这里不比较 oral 的“口部的”义（如 oral hygiene 口腔卫生）和 verbal 的“动词的”语法义（如 verbal noun 动名词）。