from my very old mwcd (sorry, I know it's a crummy book, but it's the one I have):

"mystical: having a spiritual meaning or reality that is neither apparent to the senses nor obvious to the intelligence....involving or having the nature of an individual's direct, subjective communion with god or ultimate reality (the experience of inner light)"

and better yet:

"The Creator is the beginning of life and its ending, the Great Mystery within all things and around all things, the Universal Energy....In many Native languages the word for Creator... was a verb, indicating the movement, the activity, the motion, the pulsation of this sacred, never-ending force." - Sun Bear, Dancing with the Wheel

Yeah.
That pretty well describes what I know, how I experience it. And I find it equally fascinating that we don't all feel the same. Remarkable!

But, isn't it ultimately all One? One gigantic/infinite system/illusion/being...

m