Amagnetic
A material that can not be magnetised. Magnetism is one of the properties that can effect isochronism and subsequently be detrimental to time keeping. This is one of the fundamental advantages of making components (especially balance springs) in materials such as silicon which are not effected by magnetism.
Anti-magnetic
Describes a watch movement that is protected against magnetic fields, either through using materials that are not affected by magnetism or sheltered by an antimagnetic inner case.
Demagetize
To restore a magnetized body to its neutral non-magnetised state
Magnetism
The physical phenomenon produced by the motion of electric charge, resulting in attractive and repulsive forces between objects.