mainspring - definition of mainspring - synonyms, pronunciation, spelling from Free Dictionary

Open English WordNet

Noun (1)

the most important spring in a mechanical device (especially a clock or watch); as it uncoils it drives the mechanismType of springPart of clockwork

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Webster's Dictionary (1913)

main′spring′ noun

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.

Webster’s Revised Unabridged Dictionary (1913), from GCIDE 0.54