Spirit

A spirit is literally defined as a non-corporal being or entity.

Effectively synonymous with the concept of a soul, a number of protoss have effectively reached such a state of existance, specifically Zamara and Tassadar. The Nerazim believe that Adun also reached such a stage after his sacrifice to save them from the wrath of the Conclave, ascending to a higher plane of existance.

If technopathic and pyrokinetic interactions are any indication, then machine and fire spirits appear to exist respectively. Certainly the existance of the former fits in with the teachings of the Church of Besainted Pelagius, its disciples considering their technology to be holy as per the temporal presence of the Supreme Watchmaker.