Mack:

I am inclined to demur -- I think it has very real and bounded meanings. Others, of course, may have their own variations, mixing the subject up with various icons and pictures, but that doesn't mean it has no meaning.

1. The state, quality, manner, or fact of being spiritual.

Spiritual:ADJECTIVE:
1. Of, relating to, consisting of, or having the nature of spirit; not tangible or material. See synonyms at immaterial. 2. Of, concerned with, or affecting the soul. 3. Of, from, or relating to God; deific. 4. Of or belonging to a church or religion; sacred. 5. Relating to or having the nature of spirits or a spirit; supernatural.

(American Heritage)

Spirit: 1a. The vital principle or animating force within living beings. b. Incorporeal consciousness. 2. The soul, considered as departing from the body of a person at death. 3. Spirit The Holy Spirit. 4. A supernatural being, as: a. An angel or a demon. b. A being inhabiting or embodying a particular place, object, or natural phenomenon. c. A fairy or sprite. 5a. The part of a human associated with the mind, will, and feelings: Though unable to join us today, they are with us in spirit. b. The essential nature of a person or group. ...

A