Provenance
Where it comes from.
'Element' comes from Latin elementum, 'rudiment, first principle, matter in its most basic form.' In English from around 1300 it meant earth, air, fire, or water, the ancient building blocks of everything, before chemistry gave it today's precise sense of a substance that cannot be broken down further.
'Motor' is Latin for 'mover,' from movere, 'to move.' It meant an agent that imparts motion long before it meant a machine, and only in the late 19th century did it attach itself to the automobile. The name joins the idea of essential matter to the thing that sets it in motion.