Primum Mobile is a concept in philosophy that refers to the first or highest celestial sphere that exerts influence on all other spheres. Synonyms for this term include "first mover," "prime mover," or "unmoved mover." These terms are often used in discussions of metaphysics, as they relate to the idea that there must be a source of origin or action that sets everything else in motion. Other synonyms that are sometimes used in place of Primum Mobile include "Ultimate Cause," "Creator," or "Divine Providence." Regardless of the specific term used, the concept of Primum Mobile remains a central theme in philosophical discussions of the universe and its origins.