'Hairspring' definitions:
Definition of 'hairspring'
(from WordNet)
noun
A fine spiral spring that regulates the movement of the balance wheel in a timepiece
Definition of 'Hairspring'
From: GCIDE
- Hairspring \Hair"spring`\ (-spr[i^]ng`), n. (Horology) The slender recoil spring which regulates the motion of the balance in a timepiece. [1913 Webster]