Liminal comes from the Latin word for threshold.

It refers to boundaries, doorways, portals; not this or that, old or new, but neither and both; ambiguity or disorientation that leads to new thinking; space between. Managers and coaches are liminal roles: they are both within the group, but they also bring an outside or meta perspective that the group itself does not have a vantage point to do for itself.rG1

  1. David Gray, Liminal Thinking: Create the Change You Want by Changing the Way You Think, 2016. (See notes.)