primum mobile
Pronunciation:
/-leɪ//ˌpɹaɪməm ˈmoʊbəˌli/noun
Definitions
The outermost celestial sphere of the heavens in Ptolemaic astronomy, which was believed to cause all the inner spheres to rotate.
The prime mover or first cause.
Synonyms:primus motor(by extension) The person or thing that is the main impetus for some action; a driving force.