Motive power

n. motivation behind an activity or action; ability to move; energy used to operate machinery

In thermodynamics, motive power is an agency, as water or steam, used to impart motion. Generally, motive power is defined as a natural agent, as water, steam, wind, electricity, etc., used to impart motion to machinery; a motor; a mover. The term may also define something, as a locomotive or a motor, which provides motive power to a system. In current use, motive power may be thought of as a synonym for either "work", i.e. force times distance, or "power", an effect producing motion, dependending on the context of the discussion.
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Noun
1. the power or ability to move
(synonym) locomotion, motivity
(hypernym) mobility

Synonyms and related words:
activator, animator, appliance, arouser, bunt, butt, clout, compulsion, convenience, drive, driving force, energizer, engine, enginery, facility, fixture, human dynamo, impellent, impelling force, impetus, impulse, impulsion, incentive, incitement, irresistible force, life, locomotion, machine, machinery, mechanical aid, mechanical device, mechanism, mobility, moment, momentum, motility, motivating force, motivity, motor, movableness, power, power plant, power source, propelling, propelment, propulsion, pulsion, push, pushing, restorative, shove, shoving, shunt, spark plug, stimulant, stimulator, stimulus, thrust, tonic, utility
  

n. แหล่งพลังงานที่ทำให้เคลื่อนที่, แรงที่ทำให้เคลื่อนที่