英汉解释

adj. 不成文的；口头的；没有记录的

同义词

a. ad-lib，oral，spontaneous

反义词

a.   written

参考例句

1. The unccious is the unwritten history of mankind from time unrecorded.
潜意识是未曾付诸文本的人类洪荒时代史。
2. The unconscious is the unwritten history of mankind from time unrecorded.
潜意识是未曾付诸文字的人类洪荒时期史。
3. A powered vessel should give way to sail—it is an unwritten rule of the sea.
机动船在遇到帆船时必须让其先行，这是一条不成文的航海规则。

英英解释

adj.
  1. based on custom rather than documentation
  2. using speech rather than writing
  3. said or done without having been planned or written in advance

网络释义

unwritten
未成文的; 未成文; 没有写的; 没有记录的;
unwritten law
习惯法; 最喜欢的电影:;
The Unwritten
未写之谜;
unwritten code
不成文法典;
unwritten conventions
不成文惯例;