The Collaborative International Dictionary of English v.0.48:

Falseness \False"ness\, n.
   The state of being false; contrariety to the fact;
   inaccuracy; want of integrity or uprightness; double dealing;
   unfaithfulness; treachery; perfidy; as, the falseness of a
   report, a drawing, or a singer's notes; the falseness of a
   man, or of his word.
   [1913 Webster]

WordNet (r) 3.0 (2006):

falseness
    n 1: the state of being false or untrue; "argument could not
         determine its truth or falsity" [syn: falsity,
         falseness] [ant: the true, trueness, truth,
         verity]
    2: unfaithfulness by virtue of being unreliable or treacherous
       [syn: faithlessness, falseness, fickleness,
       inconstancy]
    3: the quality of not being open or truthful; deceitful or
       hypocritical [syn: insincerity, falseness, hollowness]
       [ant: sincerity]