noun. the most important spring in a mechanical device (especially a clock or watch); as it uncoils it drives the mechanism.
- autumnal equinox
Example sentences of the word mainspring
1. Noun, singular or mass
Ideally, if you stop just short of the mainspring’s full potential, your clock will run just fine for a full week without having to get any attention from you.
2. Verb, gerund or present participle
The self-winding feature may wind the watch's mainspring a bit when you pick the watch up.