Source : Webster's Revised Unabridged Dictionary (1913)

Negativeness \Neg"a*tive*ness\, Negativity \Neg`a*tiv"i*ty\, n.
   The quality or state of being negative.

Source : WordNet®

negativity
     n 1: the disagreeable quality of one who dissents [syn: {negativeness}]
          [ant: {positiveness}]
     2: characterized by habitual skepticism and a tendency to deny
        or oppose or resist suggestions or commands [syn: {negativism}]
        [ant: {positivism}]
     3: (chemistry) the tendency of an atom or radical to attract
        electrons in the formation of an ionic bond [syn: {electronegativity}]