Huxley invented the term "agnostic" early in the 20th century to promote the notion that since supernatural beings are non-falsifiable / non-[dis]provable, there is no way you can say you know there is or isn't a god. This is called "hard" agnosticism. It isn't just that you think there might be and you just aren't sure; it's that there's no WAY to know and so no point in debating the matter.

Some pursue a "soft" agnosticism that just says I personally don't know, but in my view, that is functionally identical to theism weakly believing in a generic / deist type of god as a significant possibility. And in any case, it's not agnosticism as conceived / defined by the person to coin the term. It needs some other label to describe it.

As for atheism being "definitely no god" that is not really the case for most atheists. It is simply declining to believe for lack of evidence. It is not a knowledge position, but a belief position. Really atheism is a side effect of skepticism and critical thinking in most cases.

@mordant
I was just keeping it short and to the point !