Source : Webster's Revised Unabridged Dictionary (1913)

Diamagnetic \Di`a*mag*net"ic\, a.
   Pertaining to, or exhibiting the phenomena of, diamagnetism;
   taking, or being of a nature to take, a position at right
   angles to the lines of magnetic force. See {Paramagnetic}.

   {Diamagnetic attraction}. See under {Attraction}.

Diamagnetic \Di`a*mag*net"ic\, n.
   Any substance, as bismuth, glass, phosphorous, etc., which in
   a field of magnetic force is differently affected from the
   ordinary magnetic bodies, as iron; that is, which tends to
   take a position at right angles to the lines of magnetic
   force, and is repelled by either pole of the magnet.

Source : WordNet®

diamagnetic
     adj : relating to or exhibiting diamagnetism; slightly repelled by
           a magnet