A moot question or a moot point is something that has been previously decided or settled in law and is therefore no longer relevant. It can also be used to say that something is of no practical importance or irrelevant.
The ordinary meaning of moot is to raise an issue
On the other hand, they can both mean a matter that was uncertain or undecided, and so is open to debate.
So, be wary of moots. Bwahahaha.