PRIME MOVER

noun Etymology: translation of Medieval Latin primus motor Date: 1809 1. an initial source of motive power (as a windmill, waterwheel, turbine, or internal combustion engine) designed to receive and modify force and motion as supplied by some natural source and apply them to drive machinery, a powerful tractor or truck usually with all-wheel drive, the self-moved being that is the source of all motion, the original or most effective force in an undertaking or work