mainspring
mainsp·ring
noun
1.
the most important spring in a mechanical device (especially a clock or watch); as it uncoils it drives the mechanism
Origin
From main + spring. For figurative sense, compare spring (“source, origin”).
Related words
Broader terms
Parts
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.