The Collaborative International Dictionary of English v.0.48:

magnetic field \magnetic field\ n. (Physics)
   The space around a magnet through which it exerts magnetic
   force; a field of force surrounding a permanent magnet,
   electrical current, or a moving charged particle; called also
   magnetic flux and field of magnetic force.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

magnetic flux \magnetic flux\ n.
   1. A measure of the strength of a magnetic field over a given
      area.
      [WordNet 1.5]

   2. Same as magnetic field.
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

magnetic flux
    n 1: a measure of the strength of a magnetic field over a given
         area
    2: the lines of force surrounding a permanent magnet or a moving
       charged particle [syn: magnetic field, magnetic flux,
       flux]