noun. the most important spring in a mechanical device (especially a clock or watch); as it uncoils it drives the mechanism.
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.