A Polarity

1. The separation, alignment or orientationof something into two opposed poles.
2. Either of the two extremes of such attributes.
3. (chemistry) The dipole-dipole intermolecular forces between the slightly positively-charged end of one molecule to the negative end of another or the same molecule.
4. (grammar) The grammatical category of the affirmative and the negative.
5. (projective geometry) A duality that is an involution, i.e. has order two.