prime mover

plural prime movers

1. human sciencesThe initial agent that is the cause of all things.

   Synonyms: first cause, first mover, primum mobile, unmoved mover

2. A machine, such as a water wheel or steam engine, that receives and modifies energy as supplied by some natural source or fuel and transforms it into mechanical work
3. automotiveTractor unit. Or, more specifically, the front part of a semi-trailer type truck, i.e., the tractor to which the trailer part attaches.
4. USA military or heavy construction vehicle.
5. A person or thing that is seminal and influential.

   Seeger was a prime mover in the folk-music revival and was accepted by collegians and young people outside the South, regardless of his alleged Communist sympathies […]

   1986, R. Serge Denisoff, Tarnished Gold, page 381

   2 more examples

   "I need not remind this audience that, though Professor Summerlee, as the head of the Committee of Investigation, has been put up to speak to-night, still it is I who am the real prime mover in this business, and that it is mainly to me that any successful result must be ascribed."

   1912, Arthur Conan Doyle, The Lost World […], London; New York, N.Y.: Hodder and Stoughton, →OCLC

   This first article looked at the present situation and asks if lessons can be learned from the past, when the railways were the prime mover in the development of tourism and leisure travel.

   2021 November 17, Anthony Lambert, “How do we grow the leisure market?”, in RAIL, number 944, page 37

6. An agonist muscle.