untruthfulness

from WordNet (r) 3.0 (2006)

untruthfulness
    n 1: the quality of being untruthful [ant: {truthfulness}]

from The Collaborative International Dictionary of English v.0.48

Untruthful \Un*truth"ful\, a.
   Not truthful; unveracious; contrary to the truth or the fact.
   -- {Un*truth"ful*ly}, adv. -- {Un*truth"ful*ness}, n.
   [1913 Webster]