oral

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

比较义项：口头的，非书面的（形容词）。

• oral 本词

  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

  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）。

Compared meaning: a spoken exam (noun).

比较义项：口试（名词）。

• oral 本词

  A general, everyday word for any spoken test, used in language classes and other settings in both American and British English; not limited to a particular academic level.

  泛指任何形式口头测试的常用词，用于语言课程等各种场合，美式和英式英语都通用；不局限于某个特定的学术阶段。

  Every student in her French class has to sit a short oral at the end of the term.

  她法语班上的每个学生学期末都要参加一次简短的口试。

• viva

  A formal British English term, short for 'viva voce', for the spoken defense of a postgraduate thesis before a panel of examiners.

  英式英语中的正式说法，是 viva voce 的缩写，指研究生在一组考官面前为论文进行的口头答辩。

  In British universities, PhD candidates must pass a viva to earn their doctorate.

  在英国的大学里，博士生必须通过论文答辩才能获得学位。

Oral and viva both mean a spoken test, but oral is a general word for any spoken exam, used in both American and British English. Viva is a more formal British term, short for "viva voce", for the spoken defense of a graduate thesis.

这两个词在“口试”这个意义上很接近，但适用范围和正式程度不同：oral 是通用词，指任何形式的口头测试，美式和英式英语都常用；viva 是英式英语中更正式的说法，专指研究生论文答辩。这里不比较 oral 作形容词表示“口腔的、口头的”的意思（如 oral hygiene 口腔卫生）。