The Collaborative International Dictionary of English v.0.48:

magnetic north \magnetic north\ n.
   The direction in which the north-pointing end of a compass
   needle points; at low latitudes it is close to geographic
   (true) north, but deviates substantially from true north as
   one nears the north pole.

   Syn: north, compass north.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

magnetic north
    n 1: the direction in which a compass needle points [syn:
         north, magnetic north, compass north]