'Truthfulness' definitions:

Definition of 'truthfulness'

From: WordNet
noun
The quality of being truthful [ant: untruthfulness]

Definition of 'Truthfulness'

From: GCIDE
  • Truthful \Truth"ful\, a. Full of truth; veracious; reliable. -- {Truth"ful*ly}, adv. -- {Truth"ful*ness}, n. [1913 Webster]