1) British invention 2) Computer storage medium 3) Demagnetisation 4) Demagnetization 
Degaussing is the process of decreasing or eliminating a remnant magnetic field. It is possibly named after the Gauss unit of magnetism, which in turn is named after Carl Friedrich Gauss. Due to magnetic hysteresis it is generally not possible to reduce a magnetic field completely to zero, so degaussing typically induces a very small `known` fie.....
[n] - the process of making a (steel) ship`s hull nonmagnetic by producing an opposing magnetic field
noun the process of making a (steel) ship`s hull nonmagnetic by producing an opposing magnetic field