[1] : The Collaborative International Dictionary of English v.0.48

mainspring \main"spring`\, n.
   the principal or most important spring in a piece of
   mechanism, especially the moving spring of a watch or clock
   or the spring in a gunlock which impels the hammer. hence:
   fig. the chief or most powerful motive; the efficient cause
   of action; as, the mainspring of action.
   1913 webster

[2] : WordNet (r) 2.0

mainspring
     n : the most important spring in a mechanical device especially
         a clock or watch; as it uncoils it drives the mechanism

[3] : Moby Thesaurus II by Grady Ward, 1.0

38 moby thesaurus words for "mainspring":
   ambition, aspiration, basis, calling, cause, consideration, font,
   fount, fountain, fountainhead, goal, ground, guiding light,
   guiding star, headspring, headstream, headwater, ideal,
   inspiration, intention, lodestar, matter, mine, motive, principle,
   quarry, reason, riverhead, sake, score, source, spring, springhead,
   ulterior motive, vocation, well, wellhead, wellspring

Mainspring >> M Words
Mainspring, definition of term: Mainspring
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