Definition of overcoil in US English:

overcoil

noun

Watchmaking
  • The last coil of a Breguet hairspring, having the outer quarter turn raised and curved towards the centre to improve timekeeping.

Origin

Late 19th century; earliest use found in Frederick Britten (1843–1913). From over- + coil.

Pronunciation

overcoil

/ˈəʊvəkɔɪl/