oral

oral, verbal

这两个形容词都有“口头表达的”之意。
oral: 侧重指用嘴进行表达或交流。
verbal: 指口头进行，但不排除使用文字的可能性。

名词 oral:

1. an examination conducted by word of mouth
   同义词：oral exam, oral examination, viva voce, viva

形容词 oral:

1. using speech rather than writing
   同义词：unwritten
2. of or relating to or affecting or for use in the mouth
3. of or involving the mouth or mouth region or the surface on which the mouth is located
4. a stage in psychosexual development when the child's interest is concentrated in the mouth; fixation at this stage is said to result in dependence, selfishness, and aggression

1. My oral English is pretty rusty.
   我的英语口语全荒废了。
2. "The Cambridge Business Exams are part written, part oral."
   ＂商务剑桥英语考试一部分是笔试，一部分是口试。＂
3. The old man told us a story passed on by oral tradition.
   老人给我们讲述了一个口头流传的故事。
4. He will take an oral examination.
   他将接受口试。

o.ral

adj.（形容词）
Spoken rather than written.See Usage Note at verbal
口头的：口说的而不是书写的参见 verbal
Of or relating to the mouth:
属于或关于嘴的：
例句：
oral surgery.
口腔外科

Used in or taken through the mouth:
用于口腔或通过它而摄入的：
例句：
an oral thermometer; an oral vaccine.
口用体温计；口服菌苗

Consisting of or using speech:
构成或使用言语的：
例句：
oral instruction.
口头指令

Linguistics Articulated through the mouth only, with the nasal passages closed.
【语言学】 口腔发音的：只通过嘴、唇发音的，发音时鼻腔紧闭
Psychology Of or relating to the first stage of psychosexual development in psychoanalytic theory, during which the mouth is the chief focus of exploration and pleasure.
【心理学】 口部快感：属于或关于心理分析理论中性心理发展的第一阶段的，在此期间口通常是性活动和性快感的中心
n.（名词）
An academic examination in which questions and answers are spoken rather than written. Often used in the plural.
口试：大学里一种问题和答案均采用口头形式而非笔头的水平考试，常用复数形式

来源：
Late Latin ôr3lis
后期拉丁语 ôr3lis
from Latin ôs ôr- [mouth] * see ôs-
源自 拉丁语 ôs ôr- [嘴] *参见 ôs-

【引伸】
o.rally
adv.（副词）