in-,不，非，definable,可定义的。

1. There was something indefinable in her eyes.

她的眼神里有种难以确定的东西。

2. His head felt lighter in some indefinable way.

他的头不知为何有点晕眩。

3. She has that indefinable something that makes an actress a star.

她具备了那种使演员成为明星的说不出的特质。

4. An indefinable sadness had come over Huei - fang these last few days.

四小姐这无名的惆怅也是最近三四天内才有的.

5. These gentlemen had an indefinable mistrust of her good offices.

这些先生们对她的好意殷勤抱有难以名状的戒心.