Originally in translation of Latin primum mobile.

prime mover (plural prime movers)

1. (philosophy) The 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. (automotive) The front part of a semi-trailer type truck, i.e., the tractor to which the trailer part attaches.
4. (US) A military or heavy construction vehicle.
5. A person or thing that is seminal and influential.
   • 1912, Arthur Conan Doyle, The Lost World […], London; New York, N.Y.: Hodder and Stoughton, →OCLC ↗:

     "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."

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

     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 […]

• French: premier moteur
• German: erster Beweger
• Russian: первопричи́на
• Spanish: motor principal

• German: Antriebsaggregat, Antriebsmaschine, Kraftmaschine
• Portuguese: máquina motriz
• Russian: первичный двигатель

• Russian: тяга́ч