Ah understand your point - but to 'define' spirituality implies some sort of finite nature, and the whole basis of spirituality is its infinite nature. How God is infinite etc etc - although, not to mention the various types of variations of types of spirituality and the different paths of spirituality that people takes.

Also, as you said - yes, there does indeed need to be "some idea of what something is to say you are or have experienced it."

With that said to have "some idea of what something is", is fine and is being open to that "some idea" of what something is. It doesn't mean that something or that "some idea" has to have a certain definition. To have "some idea" is to be open to the experience of spirituality, and not necessarily having "one idea" on what the "definition" is.

And again, because of that "openness" of what that "some idea" could be, is indeed what makes it difficult to define spirituality.