noun Date: 1775 an agency (as water or steam) used to impart motion especially to machinery, something (as a locomotive or a motor) that provides ~ to a system
MOTIVE POWER
Meaning of MOTIVE POWER in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012