The Collaborative International Dictionary of English v.0.48:

Polarity \Po*lar"i*ty\, n. [Cf. F. polarit['e].]
   1. (Physics) That quality or condition of a body in virtue of
      which it exhibits opposite, or contrasted, properties or
      powers, in opposite, or contrasted, parts or directions;
      or a condition giving rise to a contrast of properties
      corresponding to a contrast of positions, as, for example,
      attraction and repulsion in the opposite parts of a
      magnet, the dissimilar phenomena corresponding to the
      different sides of a polarized ray of light, etc.
      [1913 Webster]

   2. (Geom.) A property of the conic sections by virtue of
      which a given point determines a corresponding right line
      and a given right line determines a corresponding point.
      See Polar, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

polarity
    n 1: a relation between two opposite attributes or tendencies;
         "he viewed it as a balanced polarity between good and evil"
         [syn: mutual opposition, polarity]
    2: having an indicated pole (as the distinction between positive
       and negative electric charges); "he got the polarity of the
       battery reversed"; "charges of opposite sign" [syn:
       polarity, sign]