The Collaborative International Dictionary of English v.0.48:

degauss \de*gauss"\ (d[-e]*gous"), n.
   1. To make a (steel) ship's hull nonmagnetic by applying an
      opposing magnetic field.
      [WordNet 1.5]

   2. To remove irregular magnetization in (the electron gun of
      a cathode-ray tube); -- used to improve picture quality,
      especially in computer monitors.
      [PJC]

WordNet (r) 3.0 (2006):

degauss
    v 1: make nonmagnetic; take away the magnetic properties (of);
         "demagnetize the iron shavings"; "they degaussed the ship"
         [syn: demagnetize, demagnetise, degauss] [ant:
         magnetise, magnetize]