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]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "polarity":
   Janus, N pole, S pole, ambiguity, ambivalence, antagonism,
   anteposition, antipathy, antithesis, balance, biformity,
   bifurcation, bilateral symmetry, clashing, collision, conflict,
   conformity, confrontation, confrontment, congruity, conjugation,
   consistency, contention, contradiction, contradistinction,
   contraindication, contraposition, contrariety, contrast,
   correspondence, counterposition, cross-purposes, dichotomy,
   disagreement, discrepancy, doubleness, doublethink, doubling,
   dualism, duality, duplexity, duplication, duplicity,
   dynamic symmetry, equality, equilibrium, equivocality, eurythmics,
   eurythmy, evenness, finish, halving, harmony, hostility,
   inconsistency, inimicalness, irony, keeping, magnetic axis,
   magnetic pole, multilateral symmetry, negative pole, north pole,
   opposing, oppositeness, opposition, opposure, oppugnance,
   oppugnancy, pairing, parallelism, perversity, polar opposition,
   polarization, pole, posing against, positive pole, proportion,
   proportionality, regularity, repugnance, shapeliness, showdown,
   south pole, symmetricalness, symmetry, trilateral symmetry,
   twinning, two-facedness, twoness, uniformity