unwritten
adj. 不成文的；口头的；没有记录的
例句
Without unwritten rules civilized life would be impossible.
没有不成文的规章，就不会有文明生活。
《牛津词典》
They obey the one unwritten rule that binds them all–no talking.
他们遵守那条约束他们所有人的不成文规定—不许说话。
《柯林斯英汉双解大词典》
The photographs were to be included in his as yet unwritten autobiography.
这些照片准备要收入他那尚未写的自传。
