the word ‘spirit’ is one of many concepts that evolved during that epoch we can call ‘the pre scientific universe’.
Our species has been moving on from there though. I think now it is quite feasible to render the word spirit as _self assertion_ which is a necessary characteristic not only of living things, but of everything which truly exists.
I agree that terms like spirit and soul are too loaded with pre-scientific connotations for my taste, but self assertion can create ambiguity as well in the other direction. By other direction I mean that our current phase of scientific development, by limiting the scope of consideration to phenomena which can be measured by impersonal instruments (bodies in space), has developed a bias toward under-signifying phenomenology.
The term self-assertion, for example, is adequate in my view if we understand self to be a private sensorimotive experience but not at all adequate if we flatten the notion of selfhood to apply to anything to which the term ‘itself’ can be applied. We can say that a line curve on a graph asserts itself or that a pop-up ad asserts itself, but that should not be seen as any kind of symptom of a subject’s presence.
If spirit over-signifies, then programmatic notions of ‘self-reference’ under-signify to a similar or perhaps greater extent.