1. unreasonable; unnatural; unjustifiable
あるいは、それも無理は無いのかもしれない。Then again, maybe that's understandable.
2. impossible
あの状況だと、無理でしょう？It would be impossible in that situation, wouldn't it?
3. forcible; forced; compulsory
oft. adverbially as 〜に
無理に出る必要ないわよ？You don't need to force yourself to go, you know?
4. excessive (work, etc.); immoderate
5. to work too hard; to try too hard
だから、そんな無理すんなって言ったんだ。That's why I told you not to push yourself so hard.
Interjection
Colloquialism
6. no way; not a chance; never; dream on
7. irrational