The term mover can be considered in a very comprehensive aspects. Though it simply means something or someone able to move or to be moved, its sense is expanded through a wide horizon of different characteristics. "Prime mover" can be described as the main power source of large application to run.
Typically, this term is used in industrial applications. For instance, an automobile's engine is the prime mover for it whereas the other accessories like electric generator, power steering pump, and fuel pump can be considered as secondary movers.
In case of semi trailer tractors, the entire vehicle can be said to be the prime mover. And it suits best in context of military where the howitzers used to haul a piece of artillery are considered as the prime mover.
The diesel engine is the prime mover in devices or locomotives which run with diesel or electricity as they drive the generator or alternator.
So, the term prime mover is versatile in meanings. One more meaning of it is the cosmological, theological or philosophical in terms of the some power who is maintaining the entire cosmic manifestation.
The term prime mover also fits right with respect to human beings. Individuals with some feat in a particular field like medical, Engineering or space technology are the prime movers. Inventors, industrial and military leaders are the prime movers.
Besides psychological and sociological aspects the term can also be found in context of physics. Muscles are the prime movers in context of sports which prove to be decisive in giving good performances. The evolution of mankind is owed to the human brain which is considered to be the prime mover in this case.
It might be concluded that this term prime mover came into existence with the emerge of industrial machines which worked as the prime mover for industrialization. They were the driving force. This is used as a notion by the groups or individuals to claim themselves to be the prime movers in their field