Here is another quote from the book Integral Psychology by Ken Wilber.
By the way, note the word Witness is qualified by the word supraindividual, so it is NOT the other thing..
Here are the common definitions [of spirituality]:(1) Spirituality involves the highest levels of any of the developmental lines. (2) Spirituality is the sum total of the highest levels of the developmental lines. (3) Spirituality is itself a separate developmental line. (4) Spirituality is an attitude (such as openness or love) that you can have at whatever stage you are at. (5) Spirituality basically involves peak experiences, not stages.1. Spirituality involves the highest levels of any of the developmental lines. In this definition, "spirituality" basically means the transpersonal, transrational, post-postconventional levels of any of the lines, such as our highest cognitive capacities (e.g., transrational intuition), our most evolved self (the transpersonal Self or supraindividual Witness), and so on. In this stage, spirituality (or this particular aspect of spirituality) definitely follows a sequential or stage-like course, because it is, by definition, the post-postconventional stages in any of the developmental streams. This is a very common usage, reflecting those aspects of spirituality that embody the very highest capacities, the noblest motives, the best of aspirations; the farther reaches of human nature; the most highly evolved, the growing tip, the leading edge--all of which point to the highest levels in any of the lines.
2. Spirituality is the sum total of the highest levels of the developmental lines. This is similar to the previous definition, but with a slightly different (yet important) twist. This definition, emphasizes the fact that, even though the individual lines unfold hierarchically, the sum total of the highest stages of those lines would show no such stage-like development. Like "overall development" and "overall self" development, "overall spiritual development" would not be stage-like. (Say there are ten developmental lines. Say that the post-postconventional stages of those lines are the ones we are calling "spiritual." One person might develop post-postcon capacities in lines 2 and 7. Another person, in lines 3, 5, 6, 8, and 9. Another person, in lines 1 and 5. Each of those lines is hierarchical, but the sum total obviously follows no set sequence at all.) Every person's spiritual path, in other words, is radically individual and unique, even though the particular competences themselves might follow a well-defined path. (Notice, however, that with this definition, precisely because the developmental lines themselves are still stage-like, the development in each of those lines could be tested for.) I believe that this definition, like all of them, points to some very real and important aspects of spirituality, aspects that any complete definition of spirituality would want to include.
Well I'll leave it there, if anyone is actually interested please post a message to this thread and I'll post the other definitions.