in-,不，非，formal,正式的。即不正式的，随便的。

1. Council members are due to have informal discussions later on today.

委员会成员定于今日晚些时候进行非正式讨论。

2. The two leaders will retire to Camp David for informal discussions.

两位领导人将到戴维营进行非正式讨论。

3. Our aim was that these meetings be unstructured and informal.

我们的目的是，这些会议不事先进行精心组织，要随意一些。

4. I would like it to be an informal occasion.

我希望把它办得不那么正式。

5. His friend was less good-looking, but a lot more informal and relaxed.

他的朋友没那么英俊，却随意、放松得多。